Here is an exercise with cards that may help put over what I am trying to say.

There are two genes in a gene pair. There are nine genes in the set of alleles designated the BEL complex. Make two identical lists of the nine alleles. These lists are designated List Spade and List Heart. See below. Take a pack of cards and separate out the ace of spades and the cards numbered 2 through 9 of spades. Do the same with the ace and 2 through 9 of hearts. Shuffle the spade cards and spread them out face down on your left. Shuffle the heart cards and spread them out face down on the right. Draw a spade card at random, draw a heart card at random and look at them. These make a gene pair. If the numbers on the two cards are the same, then the gene pair is homozygous. If the numbers on the two cards are different, then the gene pair is heterozygous. Replace the cards in the appropriate set and repeat. If no homozygous gene pairs have been drawn after ten gene pairs, reduce the two lists to the same three or four cards (genes). The 2, 4, and 6 cards would be a good set of three, and the 2, 4, 6, 8 cards would be a good set of four.


List Spade
Bamboo = spade ace
Butter/Lesser (platinum) = spade 2
Mocha = spade 3
Mojave = spade 4
Mystic = spade 5
Normal = spade 6
Phantom = spade 7
Russo = spade 8
Special = spade 9

List Heart
Bamboo = heart ace
Butter/Lesser (platinum) = heart 2
Mocha = heart 3
Mojave = heart 4
Mystic = heart 5
Normal = heart 6
Phantom = heart 7
Russo = heart 8
Special = heart 9