The inheritance of colorblindness gene is X linked. Sally is a female, she'll have two copies of X chromosomes. Since she is not colorblind indicates that she is a carrier of the gene, the presence of at least one functional gene on either of the X chromosome in Sally prevented colorblindness in her. The chances that her husband will have a colorblind child is 25% (1:3) and 50% for the colorblind son (1:1),based on the solved punnett square in the image, where X' denotes the colorblindness gene.
<span>It is common for some toddlers to be very shy and not be sociable. This is due to the fact that they may not have any other siblings at home and do not get out much. The fact that other children play just fine is not alarming as everyone is different than others.</span>
Much change is due to random genetic drift rather than positive selection. Some are harmful and are likely to be eliminated by natural selection – by death of the embryo, for instance. ...