"75th Wedding Anniversary" joke

An elderly couple is sharing an intimate dinner in honor of their 75th
wedding anniversary.
The man says softly, "Dear, there is something I must ask you. It has
always bothered me that our sixth child never quite looked like the
rest of our children. Now, let me assure you these 75 years have been
the most wonderful I could have hoped for, and your answer will not
take all that away. But, please tell me, did he have a different
father?"
His wife lowers her eyes, pauses for a moment, and then confesses,
"Yes. Yes, he did."
The old man tightens, very shaken, the reality hitting him hard. "Who?
Who was he? Who was the father?" he asks.
Again, the woman lowers her head, trying to muster the courage to
finally tell her husband the truth.
She says, "You."