pls help

i am an 18 year old bhumihar from samastipur, bihar. my gotra is shandilya, the problem is my grandfather and father dont know about our kuldevta/kuldevi and when i ask them where there temple is they say that they are in the form of shira ( anyone from up/bihar/jharkhand pls correct me ) and are udaasi and can be worshipped from anywhere. in my family my father, grandfather never did proper gayatri sadhana and dont wear janeu daily. i dont know whether now we are even brahmins or not .

pls tell who my kuldevi/kuldevta are, anyone from the same region pls add anything if you want