A Historical Note

"Now the sons of Reuben the firstborn of Israel, (for he was the firstborn; but, forasmuch as he defiled his father’s bed, his birthright was given unto the sons of Joseph the son of Israel: and the genealogy is not to be reckoned after the birthright. For Judah prevailed above his brethren, and of him came the chief bruler; but the birthright was Joseph’s)" (1 Chronicles 5:1-2)

So here is the quick and dirty history. I'm writing this now because 1 Chronicles gives some brief history inbetween genealogies, and I realized that they do this because no one really made the context clear in Kings, which means that I probably didn't either.
First, while Joseph got the birthright, Judah got the rulers. Remember, Ruben lost the first born right because he slept with his dad's concubine. Simeon and Levi, next in line, killed a whole city full of men to avenge their sister's rape, going against the covenant of peace that Jacob had made with them. And remember, Jacob thought that Joseph was dead this while time, so Judah was to receive the birthright (and remember, he was the one who helped save Joseph's life in the first place, so he was an ok guy). But then Joseph wasn't dead and his sons got the birthright. At that same time, Jacob blessed Judah with rulership.
But notice, it was not Ephraim and Manassah that had the priesthood right in the time of judges and kings-again, the right comes by right of righteousness, not birth. But, this is important to know historically, because after Solomon the kingdom split in two: the northern and southern Kingdoms. The southern kingdom is referred to as Judah, even though most of the tribe of Benjamin was there too. And the northern kingdom is called Ephraim in the scriptures, even though there were at least nine other tribes.
This is important to know once we start into the books of prophecy, where they talk about the return of Ephraim.
These two Kingdoms are always working against each other. But then Judah makes a pact with Assyria, and the Assyrians conquor the northern kingdom, take most of the people captive back to their country, and bring in Gentiles to supplement that area. These become the Samaritans, the offspring of these gentiles and the Israelities of the northern kingdom. And those taken away are called the lost ten tribes. But then, not shortly after, the southern kingdom is conquered by the Babylonians, and many are taken captive to Babylon, like the prophet Daniel.
Okay, I think that brings us up to speed. Sorry, wasn't a very 'brief' historical note. But, it does show that God is no respector of persons, and He doesn't care about your lineage, if you're not righteous then you're not getting the spiritual gifts. So why then does God make promises and blessings by families? Maybe, because in a perfect world, families are important. And God wants to work through family order then a kingly or priesthood order.