It it offensive to be interested in genealogy?  Is it offensive to my adopted relatives?

It depends on the person(s) involved as to whether they're offended or not. There's nothing wrong with being interested in genealogy. It should only offend the adopted relatives if there was some secret to behold.

No reasonable person would be offended by your interest in genealogy. However, your adopted relatives might be offended if you give them the impression that they're inferior to your blood relatives.

TRY NOT TO APOLOGIZE FOR BEING WHO YOU ARE--YOU CANNOT HELP BEING WHO YOU ARE

Being offensive and genealogy has NOTHING to do with the other.  Please stop labeling everything and accept words for what they mean.

That is a personal issue, however as a Genealogists for over 60 years, I believe you have a right to know your ancestral lineage, if for no other reason than medical issues, But it is offensive to include you adoptive FAMILY in your biological charts.

facts are facts

It would only be "offensive" to them if they wanted to hide them

this is YOUR history, not theirs so to be "offensive" they would have to be trying to get you to believe YOUR history is the same as theirs , which it never can be

No, that isn't offensive.

It can be, if you want to prove how "pure" your bloodline is. Adoptive parents might be offended, since it is paying attention to your bio parents instead of to them. They might not be offended; it depends on the parents.

"Is it offensive to be interested in genealogy?" No............. how your adoptive 'relations' precieve it only you will know.....  if your adoptive parents have been honest about your adoption from the begining then it is something you would discuss with them...

My oldest friend has adopted two children, one decided they wished to research and she helped them do it... she was concerned that he could face disappointment if he found his bio family and they didn't respond how he imagined they would but that is a normal reaction of any parent who loves their child, adopted or not, parents don't want their child to face unneccessary disappointments .....he found them and met them several times and was disappointed in how they responded to him/treated him and his adoptive parents were there to support him...

No, of course not. 

I have adopted cousins and they're a very real part of my family.  They're just as interested in our family history as I am and I've helped one of them trace their birth mother's family.