My mother's favorite cousin was Serena. When they were young, they lived on the same block and were best friends. They did everything together. They even lost their cherries on the same double date in the old drive-in movies.
But after high school, their lives took different directions. Mom married an intellectual whose vocation was office work, but other than performing his connubial duties, he spent countless hours at the bar, telling war stories. (Yes, at least he served his country when needed - I'll give him that.)
Serena married an adventurer, fresh out of the Marines, but he didn't have time for taverns, nor did he care to rehash the war. What he did care for was oil wildcatting. He had just enough time to give Serena two children before he was killed at a well explosion. Mom was so devastated for Serena, who never remarried - no one could measure up to her Greg.
When Serena moved back to our state (from Oklahoma to New York), she settled close enough to visit often with her mother at a private lake where our mom often brought us to see Aunt Alma (Serena's mother).
As a result, we kids were a constant summer foursome, all within two years of each other in age. Serena's children were Terrence (Terry) and Lisa, Lisa being two years younger than her brother.
I (Pete) was Terry's age, but my sister Katherine (Kitty) was only one year younger than Terry and me.
As we grew toward puberty, we made physical discoveries among ourselves (playing doctor), and it was before any of us had been given the "speech". Somehow, perhaps because of the guilty feelings this engendered, we knew enough to keep what we did a secret among ourselves.