Nepotism is a kind of corruption. It might be quite legal in some cases - private parties I think.
In some cases not as much.
It represents the appearance or actuality of kick backs and favoritism for "other" non-business reasons.
Put your mistress on the payroll? Why not! Put your 'can't get a job' brother on the payroll? Why not?!
The "princeling" hire is a classic form of quid pro quo hire - you hire Bidens coke&hookers son, his dad says hi to you on the golf course.
Nothing to see here.