What is a Punnett Square?

A Punnett square is a genetic tool used to predict the possible traits of offspring by combining parental genes. The Punnett square is a simple diagram invented by Reginald C. Punnett. It is widely used in genetics to understand how traits are inherited from parents to children. It works on the principles of Mendelian inheritance. 

By placing the alleles of one parent on the top and the other parent on the side, a square is filled to show all possible genetic combinations in the offspring.

How Does a Punnett Square Work?

1. Write the alleles of one parent on the top.
2. Write the alleles of the other parent on the side.
3. Fill in the boxes by combining alleles from top and side.
4. The boxes show possible genotypes of offspring.

Example

If one parent has alleles Tt (Tall) and the other has Tt, then the Punnett square looks like this:

From this, we see that 75% will be Tall (TT, Tt) and 25% will be Short (tt).

Uses of Punnett Square

• Helps predict inheritance of traits.
• Shows probability of genetic disorders.
• Useful in plant and animal breeding.
• Helps students understand genetics simply.