Is having ones own biological children preferred over adopting, or is it equal?
I cannot find any scholarly opinions on whether one is better than the other. From a biological perspective not having your own children means that your genes will be lost, which can have what is known as a dysgenic effect on society, reducing society’s overall fitness by reducing genetic diversity. A single person choosing not to have children is not going to have a noticeable effect in this regard, therefore it is not something to worry about unless too many people try it. Therefore as it stands, it appears to be entirely a matter of personal choice.