Are latitude lines natural or man made?

Answer 1

-- Your height and weight are natural. The systems you use to describe your height

and weight to people who can't see you are man-made.

-- The latitude and longitude of a place on Earth are natural. The systems we use to

describe the latitude and longitude of a place are man-made.

'Lines' are an irrelevant distraction in this discussion, just as the marks on the ruler

and the bathroom scale are.