Fixes brains sharing their dna with another carbon, which causes runtimes when the carbon and its dna is deleted.

code/modules/mob/living/carbon/brain/MMI.dm

@@ -91,8 +91,9 @@
 	brainmob.real_name = L.real_name
 	if(L.has_dna())
 		var/mob/living/carbon/C = L
-		brainmob.dna = C.dna
-		brainmob.dna.holder = brainmob
+		if(!brainmob.dna)
+			brainmob.dna = new /datum/dna(brainmob)
+		C.dna.copy_dna(brainmob.dna)
 	brainmob.container = src
 
 	if(ishuman(L))

code/modules/mob/living/carbon/brain/brain_item.dm

@@ -58,8 +58,9 @@
 	brainmob.timeofhostdeath = L.timeofdeath
 	if(L.has_dna())
 		var/mob/living/carbon/C = L
-		brainmob.dna = C.dna
-		brainmob.dna.holder = brainmob
+		if(!brainmob.dna)
+			brainmob.dna = new /datum/dna(brainmob)
+		C.dna.copy_dna(brainmob.dna)
 	if(L.mind)
 		L.mind.transfer_to(brainmob)
 	brainmob << "<span class='notice'>You feel slightly disoriented. That's normal when you're just a brain.</span>"

code/modules/mob/living/carbon/brain/posibrain.dm

@@ -61,8 +61,9 @@ var/global/posibrain_notif_cooldown = 0
 	brainmob.real_name = C.real_name
 	brainmob.dna = C.dna
 	if(C.has_dna())
-		brainmob.dna = C.dna
-		brainmob.dna.holder = brainmob
+		if(!brainmob.dna)
+			brainmob.dna = new /datum/dna(brainmob)
+		C.dna.copy_dna(brainmob.dna)
 	brainmob.timeofhostdeath = C.timeofdeath
 	brainmob.stat = 0
 	if(brainmob.mind)