Yes. The trait for sickle cell hemoglobin can come from either parent.
Yes. Sickle cell disease is caused by abnormal hemoglobin s. The gene for this disorder can be inherited from either parent. There are other variants as well but these also can be inherited from either parent. I would recommend genetic screening testing for sickle cell in both parents.
Supposing someone's mother is greek/macedonian and their father is african-american/dominican, what's the chance of the child getting the sickle cell trait?
Testing for parents. Only way to know is for parents to be tested first. Any ethnicity can carry the gene for sickle cell. To get sickle cell trait, just one of the parents needs to also have it. In this case, the child has 50% chance of inheriting it. If one of the parents has sickle cell disease, 100% chance that child will get trait. If both parents trait, then 25% no trait, 25% sickle cell disease, 50% trait.
Is it genetically possible for a parent with sickle cell disease to have a baby without sickle trait?
Only using a donor. The offspring of someone with ss disease wil either have trait, or if the spouse has other issues could have trait plus whatever is contributed by the spouse. If the spouse has trait, ss or trait are the potential outcomes. If the baby has none of the genes of the ss parent (thru ivf etc.) they could escape the gene.
My son has the sickle cell trait and neither his father or me have the trait. This is confirmed. How is this possible please?
New mutation. I am going to assume that a real lab study has confirmed this by hemoglobin electrophoresis and this is not a sample switch, tech error, or other cause of a bad result. Since Junior is going to ask questions, I would urge for the family's sake to do the genetic studies to confirm paternity. You are brave to ask. Best wishes.