How/When to tell my son that my husband is not his biological father??

Hey all, I know this post is quite old but I'll add to it in case anyone comes across it.Tell your child as soon as possible in terms they will understand. I was the child in this situation, almost identical to the original post, and let me tell you that now-at age 27- this is still a source of sadness and mistrust for me in my life as my parents did not inform me of my adoption until I was 15. Additionally, my biological dad is Hispanic, and my adoptive stepdad is white, so there was a lot of work that had to be done considering my cultural identity and such. In short- tell your child ASAP- have the conversation. It will likely be more difficult for you than for your young child. Children are curious by nature, and in the long run, this will build trust. Everything you read about withholding this information leading to difficulties down the road is 100% correct. I still struggle with resentment and mistrust, and now the onus is on me to forgive my parents and it is difficult. Flesh it out. Good luck.