This was originally a comment in a Facebook group, edited here to be more general—although it specifically addresses Jewish genealogy for multiple reasons. It also addresses a situation into which I ran today:
Unfortunately, there’s nothing that you can do if they do not want to take the time and effort to connect with you. On the other hand, sometimes they cannot do so due to circumstances in their lives—including possible medical conditions that may drain the energy that they would expend to genealogy (I know that Depression and other conditions that I have certainly drain me of the energy that I would expend to genealogy if I had more energy.). They may also not want to deal with anything that involves the trauma that their side of the family directly or more-directly endured (especially if a factor such as severe generational PTSD is involved. For example, I quickly figured out why one of my great-granddad Czarnecki’s siblings was not exactly mentioned: the sibling who was born before Great-Grandaunt Regina was not exactly conceived consensually—there is no record or any other indication of Great-Great-Granddad going back to Shumeve).
On the other hand, though this may not be the case, they might feel that (as I’ve unfortunately experienced with some family members and others) they’re better than you because they know more and/or at least want to think that they know more about family history and genealogy in general and/or as it specifically relates to their family history and genealogy. If they do indeed have that kind of attitude, that attitude is on them—not you—as I’ve had to learn with family members whom have that kind of attitude—and God will deal with them, especially in the days when the Temple be rebuilt and genealogies can be once again fully known and traced. By the way, the books of Ezra and Nechemya never say that God gave Ezra and Nechemya blessings to cast out the children whom were born of gentile mothers—they say only that Ezra and Nechemya claimed that they were doing so in God’s name, and that four men opposed the children being punished for the sins of the fathers (intermarriage with pagan gentile women) and (implicitly) the gentile women not being given the chance to convert to Judaism (unlike, e.g., Rut the Moabite and the Egyptian husband of Shelomit bat Divri ).
Per Sefer Ezra (JPS 1917):
“ 1 Now while Ezra prayed, and made confession, weeping and casting himself down before the house of God, there was gathered together unto him out of Israel a very great congregation of men and women and children; for the people wept very sore. {S} 2 And Shecaniah the son of Jehiel, one of the sons of Elam, answered and said unto Ezra: 'We have broken faith with our God, and have married foreign women of the peoples of the land; yet now there is hope for Israel concerning this thing. 3 Now therefore let us make a covenant with our God to put away all the wives, and such as are born of them, according to the counsel of the LORD, and of those that tremble at the commandment of our God; and let it be done according to the law. 4 Arise; for the matter belongeth unto thee, and we are with thee; be of good courage, and do it.' {P}
“5 Then arose Ezra, and made the chiefs of the priests, the Levites, and all Israel, to swear that they would do according to this word. So they swore. 6 Then Ezra rose up from before the house of God, and went into the chamber of Jehohanan the son of Eliashib; and when he came thither, he did eat no bread, nor drink water; for he mourned because of the faithlessness of them of the captivity. {S} 7 And they made proclamation throughout Judah and Jerusalem unto all the children of the captivity, that they should gather themselves together unto Jerusalem; 8 and that whosoever came not within three days, according to the counsel of the princes and the elders, all his substance should be forfeited, and himself separated from the congregation of the captivity. {S} 9 Then all the men of Judah and Benjamin gathered themselves together unto Jerusalem within the three days; it was the ninth month, on the twentieth day of the month; and all the people sat in the broad place before the house of God, trembling because of this matter, and for the great rain. {P}
10 And Ezra the priest stood up, and said unto them: 'Ye have broken faith, and have married foreign women, to increase the guilt of Israel. 11 Now therefore make confession unto the LORD, the God of your fathers, and do His pleasure; and separate yourselves from the peoples of the land, and from the foreign women.' 12 Then all the congregation answered and said with a loud voice: 'As thou hast said, so it is for us to do. 13 But the people are many, and it is a time of much rain, and we are not able to stand without, neither is this a work of one day or two; for we have greatly transgressed in this matter. 14 Let now our princes of all the congregation stand, and let all them that are in our cities that have married foreign women come at appointed times, and with them the elders of every city, and the judges thereof, until the fierce wrath of our God be turned from us, as touching this matter.' {P}
“15 Only Jonathan the son of Asahel and Jahzeiah the son of Tikvah stood up against this matter; and Meshullam and Shabbethai the Levite helped them. 16 And the children of the captivity did so. And Ezra the priest, with certain heads of fathers' houses, after their fathers' houses, and all of them by their names, were separated; and they sat down in the first day of the tenth month to examine the matter. 17 And they were finished with all the men that had married foreign women by the first day of the first month.”
In other words, Ezra went after the majority to do evil and perverted Torah to do so.
In conclusion, then, you can do nothing about what your family members do—especially if they have the haughy and self- and pseudo-righteous attitude of Ezra.