G25 authenticity check

Global25 coordinates carry a numeric signature from how they were produced. An original projection has a characteristic distribution and a consistent number of decimal places; a row that has been rounded, re-scaled, hand-edited or generated from a different calculator's output tends to depart from that in ways arithmetic can see. This tool inspects a pasted row for those departures — precision that has been lost, values that fall outside the range a real projection produces, digit patterns consistent with manual editing, and the fingerprints of a simulated rather than measured coordinate.

It matters because every downstream number inherits the input. Distances and admixture fits are arithmetic on these 25 values, so a row that was rounded to three decimals or assembled from a K36 conversion will produce clean-looking rankings that describe the conversion rather than the genome. Checking the row first is the cheapest way to avoid building an interpretation on top of a coordinate that cannot support it.

What it cannot do: this is a check on the numbers, not on provenance. It cannot prove a row is yours, cannot confirm which service produced it, and cannot certify a coordinate as genuine — a carefully constructed fake can pass, and an unusual but real coordinate can look suspicious. Read the result as evidence about how the row was probably handled, never as a verdict on the person it claims to describe. Everything runs in your browser; nothing you paste is uploaded or stored.