Blindness at birth is often "congenital" (a result of genetic flaws).
kinship
There is no one-word substitute in English for "son-in-law."
The word you want is florist.
The word "blind" has one syllable.
Sportsmanship is a word substitute for spirit of game
A congenital disease is one which is present from birth and not acquired later. Eg. a congenitally blind person is one who was blind from birth and did not become blind during their life due to an illness or accident.
The word metalworking is one word.
eat, use
The word that works is idiot.
One possible substitute for "their" is "his" or "her" depending on the gender of the person/people being referred to. Another substitute can be "its" when referring to a non-human object or entity.
Elevate
A walker is a pedestrian.