So-called happy family life means that we have a very loving wife and loving children. Thus we enjoy life. But we do not know that this enjoyment is false, that it is resting on a false platform. At once, in the twinkling of an eye, we may have to give up this enjoyment. Death is not under our control. From the Bhagavad-gita we learn that if one dies while too much attached to one's wife, the result will be that in his next life he will have the body of a woman. And if the wife is very attached to her husband, she will get a man's body in her next life. Similarly, if you are not a family man but are attached to a cat or dog, then your next life will be as a cat or dog. These are the laws of karma, or material nature.

(Srila Prabhupada — Transcendental Teachings of Prahlada Maharaja)