Actually, my siblings and I did not have happy childhoods. Many people use an unhappy childhood for bad behavior, but I don't see that as an excuse. We can learn to behave responsibly and kindly even if we have had an unhappy childhood.
Our parents never quarreled with each other and we could never turn one against the other; that was good. But we were constantly being put down; it seemed that we could never do anything right and were never good enough. We could not take problems home since if anything bad happened, it was assumed that we had done something wrong to cause it. Basically, there was no emotional support. The effect on all three of us was similar; we had trust issues. To a considerable degree one can recover from that sort of thing, but there is always a residual.
When visiting other homes, I noticed the contrast. By comparison, they were very peaceful and the parents were not constantly putting down their kids.
When I was 20, I was disowned after being outed. The shock was to some extent mitigated by my never having trusted them in the first place, but even so, it was still a horrible experience.