I am an adoptive mom to 2 kids and I would NEVER tell my kids not to go and look for their birthfamily. I find that very selfish on your moms part. I guess if I were you I would search anyway and if you find her, then that would be up to you to tell your parents.. They will just have to get over it. You are an Adult and it's only fair for you to find the anwers you are looking for..I hope it all works out for you..You will be in my prayers..
Hugs,
Cathy