Had unprotected sex with sex worker 20 years ago but blood test is hiv negative to this day.now have have family and all have bad allergy and skin rash. do you think this is related?

Not HIV: Your family having rashes / eczema and allergies has nothing whatever to do with your wild partying as a youngster. Put that thought out of your mind and focus on being as good a husband and dad as you can possibly be. It's good that you asked -- life's difficult enough without your harboring terrible thoughts like this. Best wishes.

Not likely related : If you mean by allergies - seasonal allergies to pollen, mold, pet dander, etc there that tends to run in families and cannot be "caught" from another person. Skin rashes like eczema often accompanies people with allergies and are common. Again, not contagious. Take care!

No: I agree with the previous answer. Do note that allergic diseases have a major genetic component and thus it is no surprising that other family member suffer from allergic diseases.