Walk on Water

Dallas heard that his father, grandfather and great-grandfather had all walked on water on their 21st birthdays.
So, on his 21st birthday, Dallas and his big brother Damon, headed out to the lake. "If they did it, I can too!" he insisted.
When Dallas and Damon arrived at the lake, they rented a canoe and began paddling. When they got to the middle of the lake, Dallas stepped off of the side of the boat... and nearly drowned. Furious and somewhat embarrassed, he and Damon headed for home. When Dallas arrived back at the family home, he asked his grandmother for an explanation. "Grandma, why can't I walk on water like my father, and his father, and his father before him?"
His sweet old grandmother took Dallas by the hand, looked into his eyes, and explained, "That's because your father, grandfather, and great-grandfather were born in January. You, my dear, were born in June."