u/Great-Exercise-6935

For example, after the Doctor regenerates, is Susan still biologically related to his new body? Could you still run a genetic test on Susan and any other Doctor than Hartnell to confirm that they're her grandfather?

(I'm tempted to say I remember a statement made somewhere about how Time Lords' symbiotic nuclei carry dormant "genes" of sorts that determine Time Lord familial relations, but I might be entirely misremembering that.)