What are the consequences of imbreeding?

Answer 1

Negative reactions to family members who pair off stem largely from the belief that children from such relationships may have physical and/or mental abnormalities. Newborns with genetic disorders such as spina bifida or cystic fibrosis are more likely to be born of blood relatives because previously unexpressed recessive genes are more likely to appear. First cousins are two-times more likely to bear offspring with a birth defect than children born of couples who don't share a common grandparent. If cousin couples happen to be carrying known genetic diseases, the risks faced by their offspring can jump. Experts say 1 out of 4 such children will have some sort of disorder.