I'd like to know if "related" in this excerpt from the first chapter of The Great Gatsby means "connected in some way", or "in the same family", or "belonging to the same group":
"If personality is an unbroken series of successful gestures, then there was something gorgeous about him, some heightened sensitivity to the promises of life, as if he were related to one of those intricate machines that register earthquakes ten thousand miles away."
My first reading of the term "related" here is to see the family implication, suggesting that Gatsby is somehow made of the same stuff as a machine that registers earthquakes.
However, the term does maintain a meaning that is highly similar if we instead read it to mean "in the same group" instead of "in the same family", with family here being a biological concept. To my mind there seems little significant difference between the categories of meaning you are choosing between. Connection, family, and group each seem to fit here.
However, seeing the family/biological concept as applying here is compelling also for the fact that this is an "origin story" of sorts. Gatsby is being described here for the first time and this background can be seen as an alternative to a family background or a personal history (such as the one Nick provides for himself regarding his own personal background).