it's my life

It was the first day of Third Grade in a new town for Little Johnny. As a test, his teacher went around the room and asked each of the students to count to 50. Some did very well, counting as high as 30 or 40 with just a few mistakes. Others couldn't get past 20. Johnny, however, did extremely well; he counted past 50, right up to 100 without any mistakes.
He was so excited that he ran home and told his Dad how well he had done. His Dad nodded and told him, "That's because you are from Alabama, Son."
The next day, in language class, the teacher asked the students to recite the alphabet. It's Grade Three, so most could make it half way through without much trouble. Some made it to S or T, but Little Johnny rattled off the alphabet perfectly right to the end.
That evening, Johnny once again bragged to his Dad about his prowess in his new school. His Dad, knowingly, explained to him, "That's because you are from Alabama, Son."
The next day, after Physical Education, the boys were taking showers. Johnny noted that, compared to the other boys in his grade, he seemed overly "well-endowed".
This confused him. That night he told his dad, "Dad, they all have little tiny ones, but mine is ten times bigger than theirs. Is that because I'm from Alabama?" he asked.
"No, Son," explained his Dad, "That's because you're 18."