Inheritance: how traits pass between generations — Biology, 11–13
Children receive biological instructions from both parents, but not a simple photocopy of either one. Different versions of genes combine, helping explain family resemblances and differences.
Instructions with variations
Genes are sections of DNA that carry instructions for features or body processes. You receive a version of each gene from each biological parent, so your combination is usually different from everyone else’s. Genes influence traits, but surroundings and experiences can influence how some traits appear.
Why study inheritance?
People noticed that families share features, yet children are not identical to their parents. The problem was explaining both patterns with something that could be passed on. Breeding experiments, especially Gregor Mendel’s pea plants, revealed predictable patterns; later, DNA helped explain the physical instructions behind them.
A simple flower example
Suppose purple flowers are linked to a dominant version P and white flowers to a recessive version p. A plant with Pp is purple because P masks p. Cross two Pp plants: each can pass P or p, giving PP, Pp, Pp or pp. Three of four combinations are purple, and one is white.
Dominant does not mean better
A common mistake is to think a dominant trait is stronger, healthier or more common. The word only describes what happens when two particular gene versions are together: one can affect the visible trait while the other is hidden. A recessive version is still present and can be passed on.
Families, health and breeding
Inheritance helps doctors assess the chance of some genetic conditions, though a family pattern is not a certain prediction. It also helps breeders select plants or animals with useful features. In everyday life, it explains why a family may share a blood group, a curl pattern or a risk without making anyone’s identity predictable.
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