The Grandmother Effect: How One Climate-Aware Person Can Influence the Behaviour of Five Others

I used to think climate education was about reaching as many people as possible. Then I met Savitribai in Pune, and she showed me I had the whole thing backwards. It isn’t about how many people you reach. It is about who you reach first.

The woman who changed her household without ever using the word climate

Savitribai is 67. She manages a joint household of eleven people in a working-class neighbourhood on the edge of Pune – three generations, two sons with their families, and her husband, who does not say much but does whatever she says. She has a Standard 7 education and has never read a newspaper article about climate change.

She also separates wet and dry waste every single day, has not used a single plastic bag since 2019, grows her own herbs on the windowsill, soaks lentils overnight instead of buying canned, and dries clothes in the sun even when her daughter-in-law suggests using the dryer her son brought home.

I met Savitribai through a ClimateVarsity community programme in Pune. We had run a series of evening sessions with a local women’s self-help group – simple, vernacular, video-based content on water use, waste, and household energy. She attended four sessions. Quiet throughout. Asked exactly two questions the whole time.

Six months later, when we came back to check in with the group, her daughter-in-law Priya told me something that I have been thinking about ever since.

“After aaji went to those meetings, everything changed at home,” Priya said. “The children started separating waste because aaji told them to. My husband stopped leaving the fan on because aaji complained about it. I started buying from the vegetable vendor down the road instead of the supermarket because aaji said it was better. We didn’t have a big family meeting about it. She just started doing things differently and we followed.”

What we call the grandmother effect – and why the number is probably conservative

We started noticing this pattern across our programmes before we had a name for it. One person attends a session, goes home, and something changes in the household. Not everything. Not immediately. But something. A behaviour shifts. A habit forms. And then it spreads.

We called it the grandmother effect, partly because the pattern showed up most often in older women – the ones who run the kitchen, manage the household budget, decide what gets bought and what gets thrown away. But it isn’t only grandmothers. We have seen it in a young man in Nagpur whose mother started asking him why he left the tap running while brushing his teeth. We have seen it in a schoolteacher in Mysore whose students went home and told their parents about the water cycle, and the parents started checking their overhead tank for leaks. We have seen it in a retired civil servant in Bhopal who read our content online and started talking about groundwater with his building society.

The pattern is consistent enough that we built it into our programme design. When we estimate the reach of a ClimateVarsity programme, we no longer count only the people who sit in our sessions. We count their households.

This is not unique to ClimateVarsity. The research literature on household behaviour change has documented intra-household influence for decades, across everything from nutrition programmes to sanitation campaigns to energy efficiency interventions. A 2020 review in the Journal of Consumer Research found that household members – particularly those with high social authority within the family – act as the primary socialisation agents for sustainable behaviour. Children influence parents in some contexts. Parents influence children. Grandparents, in Indian households especially, influence everyone.

The specific multiplier we see – one informed person influencing three to five others – is consistent with what behaviour change researchers call the “norm cascade” effect. Once one household member adopts a new behaviour visibly and consistently, the social norms of the household shift. Other members adjust not because they have been educated but because the behaviour has become normal.

Why the grandmother is almost always the right person to start with

I have been asked, more than once, whether the framing is reductive – whether calling it the “grandmother effect” puts too much of the climate burden on older women who already carry disproportionate household labour. It is a fair challenge. The answer is that we are not arguing grandmothers should do more work. We are arguing that in the context of climate education, they are often the most effective conduit for behaviour change, and we should design programmes accordingly.

Here is why.

They control the daily decisions that matter most

In most Indian households, the person who decides what gets cooked, how water is used, what gets bought from where, and how waste is handled is not the highest earner. It is the person who manages the domestic economy day to day. In many households, across class and geography, that is a woman in her forties, fifties, or sixties. She makes hundreds of micro-decisions every week that collectively constitute the household’s environmental footprint. If her behaviour changes, the household’s footprint changes.

They have social authority that doesn’t require argument

This is the piece that took me longest to understand. I used to think behaviour change required persuasion – information in, new behaviour out. What Savitribai taught me is that persuasion is almost irrelevant when social authority is in play. Her household didn’t debate waste separation. She started doing it, she expressed a preference, and the household followed. No lecture. No data. No WhatsApp forward.

This is what researchers call normative influence – changing behaviour not by changing beliefs but by changing what is perceived as normal within a social group. In a household, the person with the most normative authority is the person best placed to shift the household norm. In many Indian households, that is the grandmother, the mother-in-law, or the senior woman managing domestic affairs.

They often have traditional ecological knowledge that climate education can reactivate

This is the connection I find most interesting. Many of the women we work with in our community programmes already know things about sustainable living that younger generations have forgotten. They remember how their mothers stored grain without plastic. They know which vegetables are in season and which aren’t worth buying. They understand, from lived experience, that water is not infinite and that the summer of their childhood was cooler than the summer their grandchildren are growing up in.

Climate literacy, for these women, is often less about introducing new knowledge and more about validating and framing what they already know. When a 65-year-old woman in our Pune programme said “I have been telling my sons for years not to waste water, and now you’re telling me there’s a scientific reason for it,” she wasn’t discovering something new. She was finding the language to articulate what she already understood intuitively.

Three households, three different pathways to the same result

The grandmother effect doesn’t always look the same. Here are three households I have spent time with, and three different ways the pattern played out.

Pune – the quiet standard setter

Savitribai’s story, which I opened with, is the cleanest version of the effect. One person changes their behaviour. The household follows without being asked. The mechanism is social authority and visibility – she does things differently, the household adjusts.

When I asked Savitribai herself why she thought the household had changed, she looked at me as if the question was slightly strange. “Because it is the right thing to do,” she said. “And my family are good people.”

She had no theory of behaviour change. She just assumed that if she demonstrated the right behaviour, her family would recognise it and align. She was correct.

Nagpur – the child as relay

In Nagpur, the mechanism was different. We ran a programme with a community centre that included a session for school-age children. A twelve-year-old named Rohan came home and told his parents about the water harvesting session. He explained, with the particular confidence of a child who has just learned something and wants the world to know it, how much water his family was wasting when they left the tap running while washing dishes.

His mother, Anita, told me she found it slightly annoying at first. “He was correcting everything we did for about two weeks. It was a bit much.” But she also started paying attention to the tap. Her husband, who found the whole thing faintly ridiculous, nevertheless bought a water-saving tap attachment the following month. The behaviour change came through the child, but the child wasn’t the decision-maker. He was the trigger.

This child-to-parent pathway is well documented in the research. A 2022 study on children’s sustainable behaviour found that when children learn about environmental issues in a structured educational setting, they act as socialisation agents within the family – transmitting knowledge and norms upward to parents and sideways to siblings. The researchers called it “reverse socialisation.” Rohan was doing exactly that.

Mysore – the community member who became the informal educator

A woman named Lakshmi attended two of our sessions in Mysore, became interested in the water content, and started talking about it with her neighbours. Not in a formal way – over the wall while hanging washing, at the vegetable vendor, in the lane outside in the evenings. She had understood something about the connection between groundwater, borewell depth, and the concrete construction happening in her neighbourhood, and she was bothered by it.

Over about three months, she had these conversations with perhaps twenty households. We tracked this when we did our follow-up survey. Her neighbours were more likely to have reduced tap use, more likely to know their building’s borewell status, and more likely to have complained to the housing society about unchecked construction, than similar households in nearby lanes where she had no connection.

Lakshmi wasn’t a formal educator. She was just someone who had absorbed an idea that bothered her and kept talking about it. The climate content had given her a frame for something she had been vaguely worried about for years. Once she had the frame, she couldn’t stop.

The most powerful climate educators are not the ones we train. They are the ones who go home after a session and can’t stop thinking about it.

What this means for how we design programmes – and how CSR teams should think about impact

The practical implications of the grandmother effect are significant enough that they have changed how we run ClimateVarsity programmes.

We no longer design primarily for individuals. We design for households. That means thinking about who in a community has the most normative influence, and reaching them first. It means creating content that is practical, domestic, and immediately applicable – not content about global temperature averages, but content about the water coming from the tap and the waste being generated in the kitchen. It means following up with participants not just as individuals but as household influencers, asking them what changed at home.

It also means we talk differently to our CSR funding partners about what they are buying when they fund a ClimateVarsity programme.

A typical CSR programme is evaluated on direct beneficiary count. Ten lakh rupees spent, five thousand people trained, tick. What the grandmother effect shows is that this undercounts the impact by a factor of three to five. If those five thousand people each influence three to five household members, the programme has reached between fifteen thousand and twenty-five thousand people – at no additional cost.

We build this into our BRSR reporting support. When we provide data to our CSR partners, we report direct beneficiaries and estimated household reach separately, with the methodology clearly documented. It gives our partners a more accurate picture of what their investment is producing – and it gives their sustainability reports a more compelling story.

The part nobody talks about – when it doesn’t work

I want to be honest about this, because I find the unreflective version of this argument irritating when other organisations make it.

The grandmother effect is real. The multiplier is real. But it is not automatic, and it is not guaranteed, and there are conditions under which it does not happen at all.

It does not work when the knowledge is purely informational without being actionable. If someone learns that global temperatures have risen by 1.1 degrees, that is interesting. It does not give them anything to do at home tonight. Our content is designed to be immediately applicable – specific behaviours, specific decisions, specific household practices – and we think that is part of why we see the multiplier effect. Abstract knowledge does not cascade through households. Practical knowledge does.

It does not work when the participant lacks social authority within their household. We have seen this in programmes where we have primarily reached younger people – particularly young women in households where domestic decision-making is controlled by in-laws. They attend our sessions, they understand the content, and then they go home to a household where their ability to change what happens in the kitchen is limited. The knowledge is there. The agency isn’t.

And it does not work when the behaviour change required is costly in ways the household cannot absorb. We are careful not to recommend things that require upfront investment most households can’t make. The focus is always on changes that are free or net-positive – reducing water waste, shifting buying patterns, changing energy habits. Not solar panels. Not new appliances. The low-friction stuff.

Understanding these limits is not a reason to be less ambitious. It is a reason to design more carefully.

Back to Savitribai

I went back to the Pune neighbourhood six months after our follow-up visit. Savitribai was in the courtyard outside her building, sorting vegetables. She remembered me.

I asked her if she thought about what she had learned in the sessions. She considered this for a moment. “I think about the water mostly,” she said. “I think about how much we use and where it comes from. Before I didn’t think about it. Now I think about it every day.”

I asked if her family had noticed a change.

“My younger grandson asks me now where the water comes from when he turns on the tap,” she said. “I tell him it comes from the ground and from the sky and we have to be careful with it.” She paused. “He tells his friends at school.”

I didn’t ask what the friends told their parents. But I have a reasonable guess.

Climate education that stops at the person in the room is only doing a fraction of its job. The household is the unit that matters. The community is where the change lives.