Hi. I have a question about a biology.?

I'm guessing you flipped each of the pennies to determine what the child would be, or what allele was in the gamete? I did a lab sort of like this, and independent ortment is simulated by the pennies. Think about it - you have a 50/50 chance of getting heads or tails. The same happens with independent ortment: each gamete has a 50/50 chance of getting each allele. Once this is completed for all traits, the gametes are all unique. A 50% chance multiplied x times (multiply by 0.5 for each trait) gives you a pretty small chance of producing two completely identical gametes.