# The Naked Scientists Forum

### Author Topic: Why is my son's blood group different?  (Read 3423 times)

#### Rinquest, Sandra

• Guest
##### Why is my son's blood group different?
« on: 07/03/2009 13:30:02 »
Rinquest, Sandra  asked the Naked Scientists:

My blood group is A and my husband is group B.

We have 3 children.  My son's blood group is O and my daughter's are group A and group B.

Why is it that my son has a different blood group to any of us ?

Sandra

What do you think?

#### DrN

• Hero Member
• Posts: 815
##### Why is my son's blood group different?
« Reply #1 on: 07/03/2009 14:12:35 »
This is all down to which genes are passed on to your children. Essentially, you have 2 genes that determine blood group, out of A, B or O, and A and B are dominant over O.

So someone who is type A can have two 'A' genes [AA] or one A and one O [AO], someone who is type B can have two B [BB] genes or one B and one O [BO] gene.

AA - type A
AO - type A
BB - type B
BO - type B
OO - type O

For your son to be type O, you must be AO and your husband must be BO, so both of you passed on your 'O' genes to him. For the daughter who is type A, you must have passed on your A gene while your husband passed on his O gene, and for the daughter who is type B, the opposite. I've drawn a little diagram to illustrate it! Hope this helps.

Also, Wikipedia has a good entry: http://en.wikipedia.org/wiki/Blood_type

#### DrN

• Hero Member
• Posts: 815
##### Why is my son's blood group different?
« Reply #2 on: 07/03/2009 14:15:06 »
If you had a fourth child, it would also be possible for them to be AB, if you passed on your A gene and your husband passed on his B gene! So, you could have four children with 4 different blood groups!

#### The Naked Scientists Forum

##### Why is my son's blood group different?
« Reply #2 on: 07/03/2009 14:15:06 »