"But the reverse is also true: Is it fair for The Government to impose an Estate Tax and reap More Money and steal/take money away from children when their wealthy parents die?"
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They're not taking money away from the "children" (almost always adults), they are reducing the amount of money the heirs gain from the deaths of their parents. In moral terms, that is a significant difference. 
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"Someone gets Money. Why should it be The IRS?"
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That supposes that the estate tax rate is close to 100%, which is far from the truth. Some of it goes to taxes, and the rest goes to the heirs. It also implies that the IRS is the terminal destination, which is also false. And like it or not, the Founding Fathers established "Taxes, Duties, Imposts and Excises" as the primary funding source for the operation of the Country and set that down in the Constitution.