Ok. Consider the age in days or microseconds of my cousins if that makes it sound more similar. The point is that the random variable is about mappings to gene

Ok. Consider the age in days or microseconds of my cousins if that makes it sound more similar. The point is that the random variable is about mappings to general numbers. “The random variable X is a function mapping the outcome to its probability” makes as much sense as “The random variable X is a function mapping the outcome to the exponential of the square root of its probability” Those are valid definitions of two different random variables - not a general definition of “random variable”.