To blame the mother for sons cancer?

See I'm not sure about this. It's a possibility but I think you should leave it to the professionals to determine what affect smoking during pregnancy might have had. That is really sad tho that a mother would be a selfish scumbag like that and smoke while pregnant to jeopardize their child's health.

That’s not how that works at all.

During the 50's, it was perfectly OK for a pregnant woman to smoke cigarettes. They even had ashtrays in the labor and delivery rooms for them. That generation wasn't all cancerous. It isn't healthy but it's not guaranteed cancer. Unfortunately some moms are so addicted to cigarettes they can't stop during pregnancy. It's not the best, but it's reality.

Smoking while pregnant generally causes issues like poor fetal development. Not cancer, but weak lungs. Bone cancer is pretty rare and more often caused by genetic factors, not environmental. That's not to say smoking didn't create a condition where the cancer could thrive, but it is not the cause of it. How sad though. Laying blame on the parent isn't helpful for the child.

Without researching it, I very much doubt if maternal smoking can cause bone cancer. I wouldn't be surprised if smoking during pregnancy could result in a baby being born with nicotine addiction and certainly alcohol can cause birth defects, but if there's evidence it can cause cancer I'd be very surprised indeed.

To get custody on this ground the father and grandmother would have to produce medical evidence and I don't believe any such evidence exists.

As for fault, I smoked all through my one and only pregnancy, back in the days when the only warning was that the baby was likely to be smaller if the mother smoked. My obstretician, a smoker himself, certainly didn't give me any warnings at all, but I still believe my daughter's near death at the time of birth and her dangerously light weight (she was the appropriate length) could well have been caused by my smoking during pregnancy. If she had in fact died I would've seen it as my fault, but out of ignorance.

My mom didnt smoke during her pregnancy I'm told. However till like 4 years ago I was breathing in second hand smoke almost nonstop. So that doesnt help ones health. No cancer far as I know

Link to credible site listing effects of smoking on unborn children below. The TLDR version is that childhood cancer isn't listed, but there do seem to be links between a mother smoking and other fetal developmental problems.

If a very young child develops cancer, that suggests a genetic rather than environmental cause. Every woman is born with all of the eggs she will release from her ovaries during her lifetime already formed. Therefore, it's impossible for the chromosomes in those eggs to be affected by anything other than penetrating radiation during the woman's life. (This is very different to sperm which are constantly produced and therefore more susceptible to being affected by environmental factors.)

The child's bone cancer is most likely due to just sheer bad luck during the roll of the genetic dice when its father's sperm met its mother's ovum. The fact the kid's father and his mother are playing the blame game about something like this suggests they're not only ignorant, but nasty people as well.

https://www.healthline.com/health/smoking-and-pregnancy

I think it depends on what kind of cancer he has.