Traits gained during life aren't inherited
- The idea
- Predict
- See it
- Why
- Check
The idea
“If a parent gains a trait during its life, like bigger muscles, its offspring are born with it.”
Offspring look like their parents. So it seems fair that a trait the parent worked for would carry over too.
The short version
The mistake: If a parent gains a trait during its life, like bigger muscles, its offspring are born with it.
What's actually true: Offspring inherit only the DNA in the egg and sperm. Changes to a parent's body cells stay with that parent.
- Somatic cells, like muscle and skin, make up the body. Germ cells in the ovaries or testes make the gametes, eggs and sperm.
- Offspring get alleles only from an egg and a sperm. Bigger muscles, a scar or a tan change somatic cells, so they end with that individual.
- That's why populations evolve and individuals don't. Alleles, including new mutations in germ cells, become more common when their carriers leave more offspring.
On the exam: Ask where the change is. In body cells, it stays with the parent. Only DNA in eggs and sperm is passed on.