What will Jay-Z and Beyonce's baby look like?

Could Shawn Knowles Carter, Jr. look like this?

Fresh off the news that Beyonce and Jay-Z's baby will have a 2,200 square foot nursery, it seems safe to draw the following conclusions about their baby-to-be:

1. Shawn Knowles Carter, Jr. will be both very rich and very famous.
2. We can probably expect a prepubescent singing, rapping, or acting debut (see: Will Smith's kids)
3. Assuming equally likely inheritance of the traits of his/her parents, this baby could wind up with some very distinctive facial features.

This third conclusion presents an interesting question for biologists -- can we predict the likelihood that Jay-Z and Beyonce's first born inherits a particular characteristic from his or her parents, such as Jay-Z's trademark face? Focusing solely on Jay-Z's nose, the strong familial link (peep his moms and grandma here) suggests that the gene for Jay-Z's nose (and let's assume for simplicity's sake that this phenotype is controlled by just one gene) shows high penetrance (those with the gene are very likely to express the trait). The Punnett squares below account for all possible scenarios involving the inheritance of the Jay-Z Nose (JZN) gene:


Scenario #1: Trait is dominant, Jay-Z carries two copies of the JZN gene

Jay-Z's genotype: JJ
Beyonce's genotype: jj


Cross: JJ x jj

	j	j
J	Jj	Jj
J	Jj	Jj

Expected results of cross: each baby has a 100% chance of inheriting Jay-Z's nose (genotype: Jj).

Scenario #2: Trait is dominant, Jay-Z is heterozygous for the JZN gene


Jay-Z's genotype: Jj
Beyonce's genotype: jj


Cross: Jj x jj

	j	j
J	Jj	Jj
j	jj	jj

Expected results of cross: 50% chance of inheriting Jay-Z's nose (genotype: Jj), 50% chance of not inheriting the trait (genotype: jj)

Scenario #3: Trait is recessive, Jay-Z and Beyonce are both homozygous


Jay-Z's genotype: jj
Beyonce's genotype: JJ


Cross: JJ x jj

	j	j
J	Jj	Jj
J	Jj	Jj

 Expected results of cross: each baby has a 0% chance of having the trait (genotype: Jj)


Scenario #4: Trait is recessive, Jay-Z is homozygous, Beyonce is a carrier


Jay-Z's genotype: jj
Beyonce's genotype: Jj


Cross: Jj x jj

	j	j
J	Jj	Jj
j	jj	jj

Expected results of cross: each baby has a 50% chance of inheriting the recessive trait for Jay-Z's nose (genotype: jj)


Total probability
Because in this admittedly limited analysis all scenarios are equally likely, we must weight them accordingly to find the total probability:


(1/4)(100%) + (1/4)(50%) + (1/4)(0%) + (1/4)(50%) = 1/2


Conclusion
Mendelian genetics confirm the obvious -- Beyonce and Jay-Z's baby likely has a 50-50 chance of inheriting one of her father's most prominent features. Watch the Crib drops Feb 2012...stay tuned.