Are base pairs in dna similar in families.For example,do siblings have
more similar base pairs then people who aren't related.

The answer is yes, and yes; but...
Although every human (including identical twins!) and maybe even every
human cell (!) has unique DNA (I think that statement will raise some
eyebrows and cause some debate here), remember that about 99.9% of
human DNA has the same sequence as chimpanzee DNA.

The differences in DNA sequence among humans are very fine indeed;
they are even finer between siblings.

Also keep in mind that a worms DNA is 95% the same as ours...