if my dna is compared with my brother’s can our identities be differentiated?
Yes. They can tell that you are closely related, but they are different.
Unless you’re identical twins, then yes. Identical (monozygotic) twins share the same DNA.
As long as he’s not your identical twin, then yes.
See http://www.loweringthebar.net/2015/05/judge-rules-man-fathered-only-one-twin.html for more about what happens if he *is *your identical twin.
ETA: I may be third, but I took extra time for a cite.
If he’s your identical twin, then it’s going to depend on how much and what part of the DNA they’re looking at. Identical twins (that is, monozygotic twins) don’t always have identical DNA - but it’s *mostly *identical, so you have to be looking in the right place. http://www.scientificamerican.com/article/identical-twins-genes-are-not-identical/
Miss smarty pants.
Although, if you’re looking at such a level of detail that you don’t look like your twin, you might not even look like you, either. There can be small differences in genes between different parts of your body, too.
Oh, even weirder than that, just your garden variety general DNA test may not be able to tell you’re you, if you’re a chimera! http://guardianlv.com/2014/01/pregnancy-no-proof-of-motherhood-woman-was-her-own-twin-and-the-twin-was-the-mother-of-her-children/
thanks. much appreciated.