Published: 17 May, 2000

Babies get their features, looks from parents' genes

Why do babies get their parents features?

This question is not an easy one to answer because a child can resemble one parent more than the other or look like a mixture of the two. Sometimes, a child more closely resembles one of their great grandparents! What is the cause of this variation? We know, based on work performed 150 years ago by Gregor Mendel, that parents transmit basic blocks of information called genes to their children. Genes have been identified in humans that control a variety of traits such as eye and hair color, as well as the predisposition to certain diseases. Sometimes a gene contributed from one parent is expressed more strongly in their children than the same gene contributed from the other parent. In other situations, genes from both parents are equally expressed. It is difficult to predict which features will be passed from parents to their children because several different genes may play a role in the inheritance of a single trait. For example, children within a single family may display a variety of hair colors because each child inherits from their mother and father a different combination of hair color genes.

Geneticists try to understand and identify how these different outcomes result in shared or unique features. In humans about 100,000 genes are thought to be required for the development of a full grown adult from a single cell. This is an exciting year for geneticists because we are about to know the sequence of each gene that is present in a human cell. The sequencing of the human genome (see the Human Genome Project for more information) will help us to better understand how different physical traits are passed from parents to their children.