Gemara: Pinchas [the son of Eli] did not sin, as the pasuk says: "Achiya son of Achitov, the brother of Iy Kavod, the son of Pinchas, the son of Eli Hakohen" (Shmuel I, 14:3). Is it possible that he sinned, and Scripture mentions him as someone’s forefather?! Doesn’t the pasuk say: "Hashem will cut off the person who will do so an er and an oneh from the tents of Yaakov and one who brings forth an offering to Hashem" (Malachi 2:12). If he is an Israelite, he will not have an er among the scholars or an oneh among the students. If he is a kohen, he will not have a son who brings forth an offering.

Ein Ayah: Lineage has to do with internal powers that flow from earlier to later generations. Everyone possesses valuable traits containing eternal light of life and sanctity that were absorbed over time in the flesh and blood of a family’s generations. They are passed on, unless something defiles one’s seed, and become a reliable part of his spiritual inheritance. Every descendant begins the edifice of his spiritual persona from the place the previous generations reached and tries to further elevate himself.
If a person is aware of the greatness within him, which he has the potential to incorporate in his future generations, his future will indeed develop spiritually, as he sanctifies his own life quantitatively and qualitatively. However, if he brazenly lowered the power within him that was designed for the future, by defiling his own life, the present and the future are also lowered. Then things of sanctity, ethics, and wisdom separate themselves from him. He thereby confuses the way in which future generations can connect to him, for whatever they attain spiritually will not be through him.
Life includes that which exists in practice, that which is already complete, and the preparations for an ever increasing future. Its main point is the power of er, that which exists in great sages, who have already turned their potential into wisdom and full justice. The proper preparation for a good future belongs to the students, who make the future better than the present based on what they have received. These two elements work side by side in the nation to spread divine light, as the complete present and the future unite. There is no difference between what exists in the present and in the future, since the preparation for the future already exists. These ideas are encapsulated in a kohen who brings an offering. On one hand, it completes that which is necessary from the past and prepares for the future by setting the stage for ongoing service that sanctifies the person.
The gemara says that one who committed a severe sin would not be mentioned in the lineage of a good descendant in the future, because he sacrificed the prospects of the future by allowing a spirit of silliness to take him over. Therefore, any success will not be linked to him. Furthermore, if he is an Israelite, whose value is felt on an individual basis, then there is a difference between that which is complete and that which is to prepare for the future. The sinner will not have an er among scholars because his spirit will not enable something complete to exist, which can have positive power over a heart that is awake (er) and full of life based on wisdom and great action. He will not have an oneh, one who can answer the call of another as a student who repeats that which he is taught. If he is a kohen, who is supposed to serve in sanctity and bless the people with broad peace, the present and the future are all one. A meal offering can complement an animal sacrifice, to fix the past, or stand alone and represent the beginning of the future.
Since Pinchas the son of Eli was mentioned as an ancestor of a kohen family, his light and strength must have been transferred to his sons, enabling them to serve Hashem, which shows that he did not sin a terrible sin.