Can I resurrect someone using their blood or hair?

Question

Me and my group wondered what counts as a "small portion of the creature’s body". Do blood or hair count?

In the resurrection spell description, it is written:

small portion of the creature’s body still exists

and then:

The remains of a creature hit by a disintegrate spell count as a small portion of its body.

In the FAQ I found only this:

If you cast resurrection on dragonhide armor does the dragon come back to life?
Yes. The resurrection spell states that “so long as some small portion of the creature’s body still exists, it can be resurrected” and that “the condition of the remains is not a factor.” It would be up to the DM to determine the age and kind of the dragon resulting from such a spell, using the guidelines for minimum size required to make the armor in question (see page 284 in the DMG). The same would apply to any object crafted from part of a living creature, such as leather or hide armor, a necklace of boar tusks, or a cloak made from the fur of a dire weasel.

Answer 1

Yes, as long as that hair or blood was taken from the body after it died

The resurrection spell requires

So long as some small portion of the creature’s body still exists, it can be resurrected, but the portion receiving the spell must have been part of the creature’s body at the time of death.

Thus, as long as you have any part of the dead body, you can cast Resurrection on that part to bring them back. Even if the body was reduced to a fine paste by a Three Speed Robe of Blending on Liquefy setting, you can resurrect them from a sample of that paste, no matter how small.

And adventurer cannot, however, give a friend a piece of their hair while they are still alive and instruct that friend to resurrect them from it if they die, because that hair would not have been part of their body at the time of death.