You inherit all of your genes from your parents on 23 pairs of chromosomes, getting half from your mother and half from your father. But it is the ends of each of those chromosomes, called telomeres, that appear to determine how fast or how slowly you show your age and those you get from your parents, too.
Chromosomes that have long telomeres are chromosomes that are able to function longer. Short telomeres mean that the chromosomes have a short lifespan before they start malfunctioning. Telomere length shortens throughout life and appears to be linked to the aging of cells and organisms.
Studying telomeres and the factors that affect their length may give us clues that help us understand the aging process, especially why some individuals in a species have longer telomeres than others.
Researchers at the University of Lund in Sweden have studied many generations of a bird called the ringed great reed warbler, which is found in Central Sweden. By studying the warblers, they determined which inheritance factors affect the length of the telomeres in these birds. Individual birds have been studied at a lake in Sweden for 30 years. Because of the length of the study and the large amount of data available, researchers were able to compare the length of telomeres in individual newborn warbler chicks to the telomeres in their parents when they were newborn.
They found that the length of telomeres on the chromosomes in these warblers depends on both inherited and non-inherited factors. The non-inherited factors were related to the mothers, not the fathers. For example, the older a chick's mother was when the chick was born, the longer the chick's telomeres are.
This pattern is different than that seen in people. In humans, the non-inherited factors that affect the length of telomeres appear to come from the father. There is apparently a link between the father's age and the length of his child's telomeres.