joe, who has the sex chromosomes xy, has classic hemophilia, an x‑linked recessive disease. classify each person depending on whether or not joe could have inherited the hemophilia gene from him or her.

Joe, who is XY and has classic hemophilia (X‑linked recessive), must have received the hemophilia allele on his single X chromosome from a female ancestor, not from any male ancestor.

For this common textbook‑style question, the classification works like this:

• His mother – Joe could have inherited the hemophilia gene from her (she must at least be a carrier, unless the mutation arose de novo).

• His father – Joe could not have inherited the hemophilia gene from him, because fathers give sons a Y chromosome, not an X.

• His mother’s mother (maternal grandmother) – Yes, she could be the original source; she could have passed a mutant X to Joe’s mother, who then passed it to Joe.

• His mother’s father (maternal grandfather) – He could not have passed the hemophilia gene directly to Joe, but if he had hemophilia, he would have passed his mutant X to Joe’s mother, making her a carrier; in that indirect sense he can be an ancestral source.

• His father’s mother (paternal grandmother) – She cannot be the source of Joe’s X, because Joe does not inherit any X chromosome from his father’s side.

• His father’s father (paternal grandfather) – Cannot be the source for the same reason; Joe’s X comes only from his mother.

If your original problem listed specific relatives in a multiple‑choice or matching format, use this rule to classify them: only individuals on Joe’s maternal line connected to his mother’s X chromosome can be the true source of his hemophilia allele; no male relative can give an affected X directly to him, and nothing on the paternal side supplies his X at all.