Hello. This has been bugging me for a while. If I use an example to demonstrate: A nephew and his uncle and the average relatedness between them. If for some trait, say eye colour, the grandmother of the nephew carries one for Blue (B), and one for Green (G), and the grandfather of the nephew carries one for Orange (O) and one for Azure (A). No one gene is more likely than any other, so each has a 1/4 probability. The probability of the uncle inheriting B, G, O or A is 1/2. And thus the probability that they both have the same gene is 4(1/4 x 1/2)= 4/8 = 19/2. But this will make up 1/2 of the complete set of genes for the nephew. 1/2 of 1/2 (i.e. 1/4) of the complete set that the nephew has will be shared with the uncle, on average. I know that the relatedness is in fact 1/4. But is my reasoning correct? I'm assuming the 'filtering process' that occurs from the nephew's mother to the nephew - there are four possibilities, but B and G compete for a place in the nephew's mother and O and A do - has no influence on the probabilities, is this correct. It must be, but it almost seems as if it should be considered.... Thanks in advance. Nobahar.