Should people be classed as/treated like family simply because they’re blood related?

Co

We all know the saying “blood is thicker than water” but I’m sure most of us will have established at some point in our lives that that’s not the case. I feel like if you’re nobody to me, then you’ll remain nobody whether we’re related or not?

Basically my dads side of the family is huge, I’ve grown up knowing a number of close relations but other than that I could walk past a relative in the street and not even know we’re related. Apparently everyone with our surname is related in some way or another, so that’s resulted in hundreds of them adding me on Facebook.

This one guy began messaging me, flirting and telling me he wanted to fly me out to Jamaica to stay with him 🤨now, I don’t class these people as my family but I still found it weird so I pointed out we have the same last name. He said he didn’t realise, and then switched it up and started calling me “cousin”, asking me to send him money because we’re “family”. I was blunt with him because I found it disrespectful to ask me for anything anyway (we’re strangers) but I said we’re not family, we simply share the same name and you didn’t even know that 10 minutes ago so don’t bring this family rubbish to me. Now I’m being told I’m mean, cold, rude, don’t care about my ancestors and should treat family as family 🤔 he’s the only one who’s ever asked me for anything, but there’s a lot who will message me like “how come you haven’t come to see me I’m your cousin” or if I don’t contact them it’s “how can you forget about your family” but I literally don’t know them other than the fact we have the same name?!

So my question is, is it natural to suddenly have a “family” relationship with a stranger simply because you’ve been told they’re related to you?