I should have worded it better, but it is not just strictly biological children. There is an entire cultural social class above what most call "rich" that encompasses the heads of major universities, companies, investment firms, and governments that represent a fraction of one percent of the population but have consistently controlled the vast majority of capital and have gradually increased their ownership stake since the most democratized periods surrounding World War 2 (though they were only so democratized because the pool of people in consideration was smaller - part of the problem in modern global capitalism is that almost everyone on the planet is now a participant, and thus there are now billions of people to exploit and bully than millions in industrialized western states that simply cut ties to the rest of the world with the death of classical imperialism in the early 20th century).

In reality, money might not stay in one families direct hands, but upward mobility is at generational lows in the west, and in particular the number of successful new businesses, and those which elevate anyone out of the working class into either middle or upper class, are diminishing significantly[1].

[1]: https://www.imf.org/external/pubs/ft/sdn/2015/sdn1513.pdf

Would a yearly single flat tax of XX% of total net worth for every human in the world solve the problem? Essentially a literal redistribution of wealth, but could it work?

Flat taxes do not work, because the established system is one where there are two classes globally - the consumer class, that is productive to consume resources with the fruits of their labor, and the capital class, that owns the means of production and use the wealth that creates them to make more wealth.

If you take 30% of everyones income, the working class loses standard of living and upward mobility while the capitalist class reevaluates their investments to insure that, despite a 30% annual expense, you are growing your wealth regardless.

It is also a dangerous precedent. If your intention to tax sufficiently high to start peeling back the democracy distorting wealth inequality, the wealthy will just flee you, and you must remember - as they exist today, they are the arbiters of society, and dictate who lives and dies through economics. If anyone outright attacked them like that, you should expect a war in return.

That's why I said a global yearly total flat tax on total net worth, not income.

If that could be made to work and the pieces set up to work, would it be a solution?

Citation?