I am reading [1] and I didn't understand this passage:

All bilateral cases should be counted as hereditary because the proportion of affected offspring closely approximates the 50% expected with dominant inheritance.

Shouldn't the percentage be 75% with dominant inheritance?

[1]: Knudson, Alfred G. "Mutation and cancer: statistical study of retinoblastoma." Proceedings of the National Academy of Sciences 68.4 (1971): 820-823.


It depends on the genotype of P (parents). If only one parent carries the dominant allele, F1 will have the allele 50%.

D = dominant allele, d = recessive allele

P: dd x Dd

F1: Dd 50%, dd 50%

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