A picture of the eye would help. Is the white spot something in the eye or actually attached to the eye? Is the white a milky coloration or does it appear to be a raised white deformity (like a scab or a buildup of something on the eye)? Does it seem to have problems with moving around (bumping into things or walking VERY cautiously)? If it's only got a problem with 1 eye, you may not notice any problem with coordination.
While it is PROBABLY not genetic, I wouldn't use it for breeding just in case.
It's possible the gosling scratched its eye in the egg and the white you're seeing is a 'scab' or other growth in reaction to that. It's also possible that it got something in its eye after birth and was unable to get it out and the irritation caused a build up. Alternately, if the white is milky white, it's possibly a genetic issue and most likely means the goose is blind in that eye.
