One proposal is that the help provided by maiden aunts and bachelor uncles in caring and providing for the children of their brothers and sisters might suffice.

• 一种提议是，未婚单身的叔叔阿姨们在关怀和照顾他们侄子侄女时所提供的帮助可能就足以说明为什么这种基因会得以延续。