A common problem in beekeeping
"F2 aggression" is a term that is used to describe the otherwise unexplained aggression in a colony of honey bees that is often experienced in the early crosses from the offspring of a "pure" queen. The daughters are usually quite good, but often the offspring of the granddaughter can be very unpleasant to handle, to the point where they can sometimes fairly accurately be described as vicious.
One problem I have seen on a number of occasions is the result of the advice often given to beginners to obtain docile bees. What happens? It generally means a nuc headed by a pure Carniolan or Italian queen, both of which are very prolific. The colonies expand at a rapid rate, then swarm soon because not enough room is given, so one generation down. If the bees get through the winter, they build up rapidly next spring. The beekeeper gets caught out by OSR, doesn't get supers on quick enough, so the bees swarm. At this point they are in the second generation and can become aggressive. The beekeeper has only handled soft bees up to now and gets hammered.
I have handled a large number of colonies and have only ever been driven away from a hive of bees because they can't be controlled on about 10 occasions in over 50 years. Three of them were on the same day. Most of them have been traced back to a similar situation as above, but instead of blaming the pure bees or queens they have bought, the beekeepers always seem to blame what is already there.
When giving lectures I have mentioned F2 aggression on many occasions and had nodding heads and grins from other beekeepers who have obviously experienced the same thing. I have has geneticists in audiences who tell me this shouldn't happen, but it does. In a lecture at Wendover in 2014, a man spoke to me after the lecture and said that although he wasn't a geneticist he was a biologist and had worked out there was a 1 in 4 chance of aggression in the second generation, even if the first generation was docile. I have no idea if he was right or not, but that seems about the right number of occurrences to me.
Although I haven't used them myself, I have handled some of the "crosses" that have been marketed in recent years, "Greek" and "Buckfast" crosses in particular. Some of them have been quite nasty to handle as they are, but often the next generation are very difficult to handle.