US Cit UK Bio dad recent discovered. apply UK citizenship?

[Alecat68]

Hello. I, USA passport holder, recently discovered my UK biological father through DNA testing. My father unfortunately passed away just before I was able to meet him but I have many new family members in the UK (Aunts, uncles, half sister and brothers). I was wondering if I could apply for British citizenship. The US allows it with UK. How would I go about it? My new Aunt said she’d be willing to do a DNA test to prove Paternity (seeing he isn’t stated on my birth certificate). Could someone let me know if this would be possible and which costs and if I would need to hire a lawyer to file?
Thanks in advance
Regards, Alison

[secret.simon]

Which year were you born in? And was your mother married to somebody else at the time of your birth?