When pregnant, I drank some alcohol, and experimented with marijuana occasionally, so how would this affect my child biologically?

Depends/time/amout. The effect of any toxin on a developing fetus depends both on the timing and quantity involved.We know that alcohol is toxic to developing fetus, triggering birth defects & brain injury.Marijuana has been tied with smaller head size with uncertain effect on learning disabilities.The human fetus may be able to tolerate small amounts of both without visible effects but have learning issues/add later.
Unlikely much at all. I agree with dr. Mosen-- although drinking any alcohol while pregnant is a lousy idea, most likely having small amounts on occasion poses minimal risk. Same with marijuana. But, that doesn't mean zero risk. So, for your baby's sake, why not just avoid doing either one and then you won't have to worry? Imagine the guilt you would have if something were to happen! don't even chance it!
Pregnant and drinkin. Drinking , especailly, when pregnant is ill advised. However, occasional drinking and experimentaion with marijuana in the last semester of pregnancy may be least disposable to the development of alcohol fetal syndrome.