Chapter 6 of 10All chapters
Chapter 6 of 10
Genes and environment
Instructions are not destiny.
Expression
Every cell holds the same DNA and uses a different part of it. What a cell becomes depends on which genes are switched on, and that switching responds to signals from outside.
- Identical twins have identical DNA and are not identical people.
- Epigenetic marks change expression without changing the sequence.
Heritability misread
Heritability describes how much of the variation in a population tracks genetic variation. It says nothing about an individual and nothing about whether a trait can be changed.