If someone stole your DNA, could they steal your identity?

Yes

Criminals might steal DNA to use the genetic identity of their victim

yes and no

Explanation:

if someone actually stole your DNA you wouldn't be alive right now,

but if someone stole "parts" of your DNA you would still be the same person because it doesn't matter what you look like you are your own person an example of this are identical twins, identical twins share the same exact DNA but they aren't the exact same person since they both can like different stuff and have different personalities. but if you mean in a biological stand point "if someone stole your DNA, could they steal your identity" of course not, at least not with our technology.

also what an odd question I like it :)

you dont brother god luck