Is hay fever hereditary?

Yes, but that doesn't mean that a child will automatically get hayfever just because one or both of his/her parents has it. If one parent has an allergy there is a 1 in 3 chance that each of their children will have allergies, if both parents have allergies there is a 2 in 3 chance that each of their children will have allergies. (In practical terms, that means if an allergic and a non-allergic person have three children together, it is likely that one will have allergies and two will not, and if two allergic parents have three children, then it is likely that two of their children will have allergies and one will not, although because of the way statistics work, in both cases it is possible that either all, none or any given number in between of the children will have allergies, however big the families)

Also, a hayfever allergy in the parent might not show itself as hayfever in the child - eczema, asthma, hayfever and other allergies are all closely linked and what comes out as hayfever in the parent could come out as asthma or another allergy in the child or vice versa. It's also very common for people to have several allergies, not just one.

Yes, you get it from your mom.

oh yes. my mom had it my brother has it i have it my kids have it and my grandkids have it. oh what fun we are in the spring
...LOL... sneeze a lot we go ...LOL

Good question! Because my sister's son has terrible allergies and is allergic to dogs and cats just like my sister. He is only 3 years old and has been allergic since birth. Weird, eh?