In the context of human society, a family is a group of people affiliated by consanguinity (by recognized birth), affinity (by marriage), or co-residence (as implied by the etymology of the English word "family") and/or shared consumption (see nurture kinship). Members of the immediate family includes spouses, parents, brothers, sisters, sons and/or daughters. Members of the extended family may include grandparents, aunts, uncles, cousins, nephews, nieces and/or siblings-in-law.
In most societies, the family is the principal institution for the socialization of children. As the basic unit for raising children, anthropologists generally classify most family organization as matrifocal (a mother and her children); conjugal (a husband, his wife, and children; also called the nuclear family); avuncular (for example, a grandparent, a brother, his sister, and her children); or extended (parents and children co-reside with other members of one parent's family). Sexual relations among the members are regulated by rules concerning incest such as the incest taboo.
French Frog comments:
I think the current nuclear family is not so favorable to B/M relationships. Ideally, the boylover is a helping hand to the family of the boy, giving some occasional break to the parents and assuming roles they can't for the emotional development of the kid. But the nuclear family implies isolation from the rest of the world. It puts a lot of pressure on the parents, yet denies them to seek help around them. So the boylover may have a hard time integrating this universe.
A community-based family model, as it existed in previous centuries (before the industrial revolution), would be much more favorable to BL relationships. The hysteria about the "dangerous stranger" would probably largely decrease, too, I guess. And boylovers would naturally get their place in the family.