One of the Lives
Our speaker is an adult, who's lying sick in an old farmhouse. He's retelling the (very indirect) history of how he came to be, but without giving us a ton of detail. He's also not letting things get too personal. He begins by talking about people who had no direct or lasting connection to his family. Then, instead of telling the romantic story of how his grandparents or parents met, he goes about it in kind of a strange, side-glancing way. He's not sappy or sentimental about any of this. He just gives us the facts. He's in a thoughtful, reflective mood, and you get the sense that he is personally invested in these events. As the poem progresses, he lets us in on more personal stuff about his mom and dad, and eventually a tiny bit about him, too.
This is a bit odd, to say the least. Usually when you see "I" in a poem, you should brace yourself for a serious case of personal, diary-style T.M.I. In the case of this speaker, though, he doesn't make it all about himself. In a way, though, much of these other goings-on are about the speaker, insofar as they contributed to him laying on this cot and rapping at us about plums. It's as if the speaker is sharing the very personal, and ironic, reflection that his life is really not all about him. He's locating himself in a continuous chain of "if-then" moments in time. Trippy.