Someone told me that more children of olim raised in Israel "leave the Derech" to become less religious than if they were to have stayed in America. Accordingly, would it then actually be halachically "wrong" to make aliya, if I have teenage children?

It's very unfortunate your friend feels that way (perhaps he's influenced by the stereotype which may have been the case 50 years ago when the anti-religious ran the country, or by the secular Israelis who live in America...), for living in Israel is itself a mitzva like Shabbat or laying tefilin, and it's like saying: "Observing Shabbat or tefillin may make you less religious". Living in Israel also enables one to do so many more other mitzvot which don't apply outside, in fact, every single second you are in the Land if Israel is another mitzva (Sefer HaChareidim, ch. 59). In other words, it's not because (!) of the Land of Israel that some people seemingly become less religious but it's despite (!) the Land. Those same people would automatically and by definition be less religious in America. I don't know your friend or his circles, but my personal experience of 30 years of educating 18 year olds in many various gap-year yeshiva programs in Israel, have clearly shown the exact opposite. Students staying in Israel generally marry more Torah-oriented spouses and build here strong homes of Torah, living in stronger Torah communities, compared with their friends who don't make aliya. Statistics also contradict your friend's feelings or limited circle impressions. In different studies done in America (by PEW and the OU), the outcomes range from 33%-56% of those who are raised orthodox there, don't stay so, while in Israel (done by HLMS), the studies found that less leave (from 21%-43%). The varied numbers are based upon how wide the definition of "orthodox" is and whom they are surveying. The 21% number is among Torani yeshiva high school students, while the 43% number counts all those who were enrolled in public religious high schools (which includes those from non-religious families who may send to those public religious schools to pacify grandparents; to distance from the more problematic youth in the regular public schools; many traditional families who aren't really orthodox; and tens of thousands of olim from Ethiopia and the former Soviet Union who, in order to convert, their families must send them to religious schooling). Accordingly, if you were to compare truly parallel groups/yeshivas/families, say yeshiva Torani families in Israel and the U.S., or marginally religious families in both places, the "retention" group in Israel is higher. It's also important to understand the significant difference in the cause of those who leave the Derech. In Israel, the pressure of army life (which is also an important mitzva in unto itself!) makes regular functioning difficult in every other sphere during those "abnormal" years, and once there is that drop, it may also follow in the future. Here the solution is obvious, to insure that our boys do their army service in the Hesder or Nachal charedi frameworks, where halachic observance is actually built into the system and there is a positive and supportive peer pressure during that period. On the other hand, in the U.S. peer pressure of being like the non-Jewish norm and majority (98%!), continues throughout life and follows you where ever you may go. Also, a study on this topic in the States, found that those who leave the Derech while on college campuses etc. generally "evaporate" from vision and simply aren't seen anymore in the community, for they leave home to distant places, don't show up in shul etc. On the other hand, in Israel, thank God, even those who "leave the Derech", "stick around" in their families, homes etc. Israel is a very small country and much more family-oriented than western culture (in addition to the high price of rent which encourages many to continue living at home), so those who don't stay religious are accordingly much more visible here, which surely contributes to your friend's "optical illusion". I will concede that specifically among Anglo olim to whom you refer, the children are often raised in pro-active and "gutsy" homes, which enabled those parents to "rebel" against the gashmiut and physical pleasures of their own upbringing in America and "make the move". This environment may logically also have a tendency to raise children who also "change course" in the opposite direction! In other words, those who leave are sometimes an expression of their environmental upbringing, and such parents would raise such children wherever they would be. The solution: consider what type of spouse to marry. Ironically, also sometime Anglo parents are more permissive, and even go out of their way to make a conscious effort to live in Anglo communities in Israel, and keep American language and culture in their homes, often reminiscing or praising American products and appliances despite (!) being in Israel. Also, some Anglo parents here may justify investing less effort into educating their kids, thinking that here they have less to worry about. On the other hand in America, parents must make a conscious effort to do the opposite, always stress the Jewish environment in the home. America is not the solution but rather the problem, and the answer is to try and keep "America" out of our homes in Israel, as well. Also, even those who do leave the Derech in Israel will still marry Jews (even the 250,000 non-Jewish olim from the former Soviet Union are only about 3% of the population), and very often return to a certain extent to tradition when they have children of school age. Contrarily, outside of Israel, it's logical for those who leave the Derech to marry gentiles (who are 98% of the population there!) where the prospect of their and their children's return are miniscule, not to mention that half of those grandchildren aren't even Jewish. How much more so when today, the Torah center of the world is in Israel, and young people come from all over the world to study in yeshiva, davka in the Land of Israel, this is the place to raise our children. Even if theoretically (!) you were to be correct in saying it is more problematic to raise children in Israel, our sages taught that it's better to even live in a city of idolaters (!) in the Land of Israel, rather than in a city of religious Jews outside of Israel (K'tuvot 110, Shulchan Aruch Ev.H. 75). To understand that surprising statement, see my elaboration at: https://www.yeshiva.co/midrash/10931 In short, in today's world, there's no guarantees anywhere regarding your children's future spirituality, but when you make the decision to make aliya, you are at least ensuring that they and their children will be Jewish, and will be around in Y'mot HaMashiach, will be doing that many more mitzvot & will be in contact with more idealistic and impressive Torah personalities. Not to mention that you will be following the guidance of our sages who already answered your question 1,800 years ago, even when the atmosphere in Israel was idolatress! You and your children will also be an active part of the most glorious chapter in Jewish history: the gathering of the exiles and the redemption! With Love of Israel, Rav Ari Shvat