Probably a background in the tendencies of progressive liberals, the left or they started within a left anarchist context. Some involved in college activism might see how they don't need government intervention so become anarchists, perhaps seeing it as one more aspect of their identity. For co-ops and collective houses, there is a long market anarchist history tied up with them (mutualist and collectivist tendencies). People like Noam Chomsky provide an entrance for a lot of people to anarchist ideas and because they don't have much difference with the left, a lot of anarchists might think it is okay to follow their example.
On the flip side, anarchists that want to be an example might benefit from being more accessible to where ever anarchists seem to generally come from and have strong, explicit views on how they think anarchists should practice. There is this large attempt by anarchists to be broadly accessible, hoping that we get a demographic that more accurately reflects general society as a whole.
What we seem to get is primarily a lower middle class and working class mix. Though anarchists are staying anarchists longer than before with more and more anarchists still identifying as they grow past their 30s, the age of anarchists is still rather young.
I'd say this reason is because we haven't attempted to adapt a stronger critique of the family and presented a viable practice for anarchists who are attempting to raise families. When anarchists have children, often the anarchist mantle is hung up. Where this isn't true, it would be more interesting to hear about and how child rearing is done with parents capable of getting arrested for their practices.
There is the issue of the government and family services intervening in an anarchist parents life, taking children from anarchists should they raise them in a way that is contrary to acceptable norms. Eventually it would be nice to see anarchists raising anarchist children as well as still attracting people that weren't starting as anarchists to become anarchists.
Though I don't want to put a lot of pressure on parents, much of this weighs on anarchist parents as the guardians of children. They decide how they'd like to raise their children. If an anarchist parent offers input and perhaps want to see multiple parent families, but the other in the couple disagrees, custody would typically go in the non-anarchist parent's direction should a split occur due to disagreement.
Imagine an anarchist parent teaching their children graffiti, vandalism, bomb making. Imagine anarchist parents exposing their children to anarchist theory and encouraging the children to form juvenile gangs with analysis. These types of things just seem to only be able to exist as a fantasy. Yet professional criminal parents often teach their children how to commit crimes, even having their children assist them in criminal endeavors. Passing their crafts from parent to child.
Itinerants and particular types of deviants or oppressed people have different social norms than the status quo also seem to be able to continue their ways of life and conflict greatly with family services and juvenile courts. These might need to be examined and anarchist parents might need to break ties with their extended families to raise their children in ways that might "endanger" their children. As I have no children, I can't exactly suggest a way to raise kids, but I do think if we want to see anarchists offer a critique of reform, we also have to be able to have a full way of life that is viable enough to cross generations.