The words “VaYedabeir Hashem El Moshe Acharei Mot Shnei Bnei Aharon,” “God spoke to Moshe after the deaths of Aharon’s two sons” (VaYikra 16:1) mark the beginning of Parashat Acharei Mot that we read last week, but they might be more relevant to Parashat Emor, which begins with laws that should be directly relevant to the deaths of Aharon’s sons. The first topic in Emor is the Halachot that describe what Kohanim, like Aharon, can and cannot do after the deaths of family members, like the deceased Nadav and Avihu, Aharon’s sons.
God tells Moshe to tell the sons of Aharon that a Kohein cannot make himself Tamei, impure, by touching a dead body for any reason, except upon the death of a member of his immediate family: his parents, children, or siblings (21:2). But even for the death of one of these family members, he may not shave any part of his head or beard, and he may not cut himself in grief (21:5).
The Kohein Gadol faces different, more stringent restrictions upon the death of an immediate family member. He is never allowed to touch a dead body, not even those of his beloved parents (21:11). Contrary to a regular Kohein, he is forbidden to grow out his hair, and he may not tear his clothing (21:10). And he may not leave the Mishkan to mourn; he must stay and continue the holy Avodah (21:12).
As alluded to above, Sefer VaYikra contains the perfect story in which we should be able to see these Halachot in action. Nadav and Avihu, sons of Aharon, die while bringing an unwanted Korban to Hashem (10:1-2). According to the Halachah mentioned here, Aharon, as Kohein Gadol, should be required to continue the usual Avodah and should be barred from growing out his hair or tearing his clothing. However, his remaining sons, Elazar and Itamar, are just regular Kohanim, and should therefore be allowed to touch, bury, and mourn for their dead brothers. They should also be required to grow out their hair and beards.
And indeed, Moshe’s instructions to Aharon follow these Halachot precisely. Moshe instructs Aharon to do exactly what we would expect of a Kohein Gadol: not to grow out his hair or tear his clothes (10:6) and to remain in the Mishkan (10:7) to do the Avodah.
But peculiarly, Moshe also gives Elazar and Itamar the exact same instructions as Aharon; they are also forbidden to mourn. So instead of burying their dead brothers, they watch helplessly as their cousins drag Nadav’s and Avihu’s bodies by their tunics all the way from the Mishkan to the edge of the camp (10:4-5).
Why are Elazar and Itamar assigned the Halachot of the Kohein Gadol with regard to the deaths of Nadav and Avihu?
Rashbam (VaYikra 10:6-7 s.v. Rosheichem Al Tifra’u) answers this question. He points out that the reason stated by the Torah in Parashat Emor as to why the Kohein Gadol is barred from mourning is that the Kohein Gadol has been sanctified with God’s anointing oil (10:7). Putting the puzzle pieces together, Rashbam concludes that Elazar and Itamar take on the Halachot of the Kohein Gadol with regard to dead relatives and thus are commanded to stay in the Mishkan because they, like their father, were anointed with oil at their inauguration as Kohanim (8:30).
We now understand why Aharon’s sons are required to observe the Halachot of the Kohein Gadol. But this brings up a second question--if they are considered like the Kohein Gadol, why does Moshe bother telling them, “HaKohanim, Bnei Aharon,” “the Kohanim, [Elazar and Itamar,] the sons of Aharon” (21:1), when the Halachot are not applicable to them?
Perhaps a comment of the Gemara (Yevamot 114a) can explain this difficulty. The Gemara notes that the first Pasuk of Emor contains a seemingly superfluous phrase: “VaYomer Hashem El Moshe, Emor El HaKohanim Bnei Aharon, VeAmarta Aleihem LeNefesh Lo Yitama BeAmav,” “God said to Moshe, ‘Speak to the Kohanim, the sons of Aharon, and tell them that they may not become impure for his relatives” (21:1). The Gemara explains that the words “VeAmarta Aleihem,” which appeared at first to be redundant, actually teach a vital lesson: “Emor VeAmarta--Lehaz’hir Gedolim Al HaKetanim,” “[the purpose of both words] ‘Emor’ and ‘VeAmarta’ is for adults to warn their children” about the dangers of Tum’ah. The children of Kohanim must be ingrained from a young age by their parents with the ideas that their purity is incredibly important and that they must be incredibly careful around transmitters of impurity.
Parashat Emor teaches us the obligation of parents to edcuate their children. Elazar and Itamar, having been anointed with oil, just as their father was, followed the laws of Tum’ah that normally applied only to the Kohein Gadol. Even though the laws of Tum’ah for ordinary Kohanim did not apply to Elazar and Itamar, they were nevertheless taught the Halachot in order to relay them to their children. If Elazar and Itamar taught their children Halachot which they themselves did not even need to keep, how much more so must we teach our children all of the Torah which we are commanded personally to uphold. Knowledge of Torah and Halachot is paramount, and there are no better people than parents to pass it along.
 Technically, the Kohein Gadol is almost never allowed to touch a dead body; if the Kohein Gadol comes across a Meit Mitzva, a dead body lying in a field, and there is nobody else to bury it, the Kohein Gadol is required to bury the body, becoming Tamei in the process.
 First cousins once removed, to be exact.