Let’s Remember

You’ve learned that:

• Genes are tiny parts inside your body that give instructions.

• They live inside every cell.

• They help build your body and brain.

• They want to stay copied — that’s how they keep going.

But here’s a new question:

Why do genes seem to “care” about family?

Let’s find out.

👩‍👧 What Is “Kin”?

“Kin” means people who are related to you.

That includes:

• Your mom and dad

• Your brothers and sisters

• Your grandparents

• Even your cousins

These people share some of the same genes as you.

Not all the same — but some!

The more closely someone is related to you, the more genes you both share.

🧮 How Many Genes Do You Share?

Here’s a simple list:

• With your parents → about 50% shared

• With your brother or sister → about 50% shared

• With your grandparents → about 25%

• With your cousin → about 12.5%

• With a stranger → maybe 0% (or very little)

This means:
Your mom has half of the same gene copies as you.
Your brother does too.
But your cousin? Only a little.

🧠 Why Would Genes “Care” About This?

Remember:

Genes want to get copied into the future.

Usually, they do that by making you have children.

But if you can’t have kids — or even if you can, there’s another way.

Helping your family’s genes is almost like helping your own.

That’s because:

Some of your genes live inside your family members too!

🐒 Let’s Look at Animals

Imagine two monkeys:

• One monkey gets food but eats it all

• Another monkey shares food with her sister

Which one helps shared genes survive?

The second monkey!

Because:

• Her sister has many of the same genes

• Helping her sister helps those same genes

This is why animals (and people!) sometimes:

• Help their family

• Protect their group

• Share, care, and even take risks

It’s not just about being “nice” — it’s also about gene survival.

💡 Helping Family = Helping Genes

Here’s the big idea:

Helping your family helps your shared genes live on.

Scientists call this kin selection.

That’s just a fancy word that means:

Choosing to help family — because your genes live in them too.

Even if you don’t realize it, this is a deep part of why families stick together.

🧠 Recap

✅ “Kin” means people who share some of your genes
✅ Parents and siblings share about 50% of your genes
✅ Helping your family is like helping your own genes
✅ This idea is called kin selection
✅ It helps explain why we care so much about family