[General] Blood Status Information

I N T R O D U C T I O N:

J.K. Rowling. Brilliant storyteller, not such a great geneticist! This is a brief guide to the different combinations of bloodstatuses than occur in the Wizarding World as it is roleplayed on Magical Hogwarts, together with explanations of some of the rarer cases that can occur. Please note that we have not included tables of dominant/recessive genes as these do not fully explain such things as squibs and muggleborns both existing together. With that in mind, please read on!

M U G G L E B O R N

Common occurrences:

muggle + muggle = muggleborn

Usually, there is only one muggleborn child per family. The only canon exception to this is the Creevey brothers, and as such, muggleborn siblings are generally discouraged on magical Hogwarts unless both are going to be played. if the child has a squib grandparent but neither parent has magical ability they will still be considered muggleborn. Furthermore, in canon it is suggested that muggleborns are likely to have a squib somewhere in their ancestry. If the squib is a grandparent the child will still be a muggleborn, though in this case they would have one set of pureblood great-grandparents.


H A L F B L O O D

Common occurrences:


halfblood + pureblood = halfblood
halfblood + halfblood = halfblood
muggleborn + pureblood = halfblood
muggleborn + halfblood = halfblood
muggleborn + muggleborn = halfblood
muggle + pureblood = halfblood
muggle + halfblood = halfblood
muggle + muggleborn = halfblood

Halfbloods would seem more common than other blood statuses judging from this list  - though depending on family history, a character who has a long pureblood lineage on one side and a halfblood parent on the other side may publicly claim to be a pureblood. Their bloodstatus would still be listed as halfblood, however. 

Rare occurrences:

muggleborn + squib = halfblood
halfblood + squib = halfblood
wizard + veela = halfblood
wizard + giant = halfblood
wizard + goblin = halfblood


P U R E B L O O D

Common occurrences:

pureblood + pureblood = pureblood

Rare occurrences:

pureblood + squib = pureblood
squib + squib = squib or small chance of pureblood


S Q U I B S

Rare occurrences:

pureblood + pureblood = squib
muggle + squib = muggle or very small chance of halfblood
 
On Magical Hogwarts, the word "squib" is used to define the non-magical child of two purebloods. These are very rare and squib occurrence probably accounts for much less than 1% of all pureblood births. Furthermore, as mentioned above, magic can lie dormant for a few generations, so a squib who marries a muggle might well find themselves the proud grandparent or great-grandparent of an apparently muggleborn child!