Distribution of sex chromosomes in female (A) and male (B) F2s depending on male or female F0 lineage. F1 and F2 animals were generated in two ways: (i) by crossing male B6.LDLR–/– mice to female FVB.LDLR–/– mice and (ii) by crossing male FVB.LDLR–/– mice to female B6.LDLR–/– mice. Arrows indicate X and Y chromosomes that are passed through from the F0 via male F1s to the F2 generation without recombination, being of F0 lineage and thus 100% FVB or 100% B6. The X chromosome, inherited from the female F1, will carry on average 50% FVB and 50% B6 alleles. Thus, in females (A) 75% of the alleles on X will originate from the female F0, and in males (B) 100% of the alleles on Y will originate from the male F0.