Question
My child has been born and their eyes keep watering, and they always seem to be crying. Can color blindness in fathers be inherited by their children?
Answer
Color blindness is not always caused by genetic factors; some individuals may have acquired visual impairments. The human chromosomes are present in pairs (with certain exceptions not considered here), and the genes on these chromosomes determine a person’s traits. For convenience, the genes on chromosomes can be represented by paired uppercase or lowercase English letters. Uppercase letters represent dominant genes that lead to the trait, while lowercase letters correspond to recessive genes. In this example, the uppercase R corresponds to the dominant gene for color blindness, and r represents the recessive gene for color blindness. RR indicates that the child has inherited one dominant gene from each parent, Rr means the child has inherited one dominant gene from one parent and one recessive gene from the other (these genes could be the dominant one from the father and the recessive one from the mother, or vice versa), and rr means the child has inherited two recessive genes from both parents. For chromosomal genetic diseases, there are two types: one is a chromosomal recessive genetic disease, which only occurs when both genes contain rr. The other is a chromosomal dominant genetic disease.