The full moon brings on all new therians. Doesn’t matter the breed it’s always the full moon. But like vampires there are several variations of therians.
My mother was the rarest of them being a carrier. A human who carries the therian virus in her. It manipulates the basic DNA but it is not affected by the turn of the moon. A carrier can pass on the DNA. A child born of a carrier and a human can become a carrier or be ‘born’ a therian. But if a carrier mates with a therian of the same breed the children are guaranteed to be therian as are all therian/therian children.
A human who is bitten by a therian and changes becomes therian. All their children will be like them, except the children are born, and not turned. The biggest and only difference between a born therian and a turned one is the when they change.
A bitten human that turns does so on the next full moon regardless of age. A child of ten can become a therian.
But a born therian, turns in their mid-twenties on a random full moon. There is no real predictability to it which is why the best course of action for all children of therians is to educate them early of what they need to do around the full moon. Especially once they turn 20.
Funny thing – I’m going to have to do this with my brothers soon rather than later. I don’t know that in story yet, but I’m pretty sure I dropped that at one point. It is very possible one or both of my brothers could turn furry once a month.