The connection between the parshios of Shimini and Tazria - the purity of children

Question

I read in Rabbi Elimelech Biderman's Torah Wellsprings the following:

Parashas Tazria discusses the laws of childbirth. These laws follow parashas Shmini, which discusses the laws of kashrus. The Ramban explains that this juxtaposition, (of kashrus and childbirth,) hints that good children are the result of parents and children who are careful with kashrus.

I like the connection but I have checked in the Ramban and he doesn't say this anywhere (at least where I have checked?)

Does anyone know a source for this / does any other commentator say this vort?

Answer 1

אגרת הקודש לרמב"ן - הדרך השלישי – המזון הראוי לחבור

והנה אם כן כשאמרו (נדה עא א) שצריך אדם לקדש עצמו בשעת תשמיש, הנה גם המזון כלול בקדוש הזה כי ראוי לאדם לאכול מזונות ראוים והגונים ממוצעים בין הקור והחום, ויהיו מן הדברים המולידים דם נקי וזך וטהור מאחר שאותו הדם עתיד להיות נהפך לטפת הזרע והוא עתיד להיות יסוד ובנין לולד הנולד מאותו חבור, כי אלו היה המזון רע ועכור ועב תהיה גם הטפה עבה מטונפת ועכורה. ואם כן נמצא המזון [הנלקח טרם החבור הוא סבה] (להויית האדם הכנה) להיות [הולד] חכם או פתי או צדיק או רשע. והנני מוסר בידך מפתח גדול. דע כי בהיות הדבר כמו שאנו אומרים, סמך השם יתברך בתורתו הקדושה פרשת אשה כי תזריע למאכלות אסורות ואמר (ויקרא יא) ולהבדיל בין הטמא ובין הטהור ובין החיה הנאכלת ובין החיה אשר לא תאכל, וסמיך ליה אשה כי תזריע, וסמך מצד אחר פרשת נגעים. ואלו הג' פרשיות לסודות נפלאים. ופרשה כי תזריע באמצע להודיע שאם יבדל אדם מן המאכלות הרעים הויין לו בנים הגונים קדושים וטהורים, ואם לאו הרי נגעים מתחדשים עליהם מצד טפת הזרע שהיתה מאותן מאכלות האסורות והמשוקצות. ועל ידי כן בא להודיעך כי צריך האדם לקדש עצמו גם במאכלות הגונות סמוך לתשמיש כדי שיהיה מזרע נקי וטהור ובינוני בין צפון לדרום כמו שאמרנו. והנה הודענוך כי כפי המזון יהיה הדם הנולד, וכפי הדם יהיה הזרע, וכפי הזרע יהיה הולד הנולד ממנו. וכבר ידעת מה שאמרנו שלא יולד מן הסוס נשר ולא מן החטה עדשים, וכן נאמר כי לא יולד מן הזרע העכור והרע כי אם דם משוקץ ונתעב כאמרו (תהלים נח) זורו רשעים מרחם. והנה הודענוך בדרך הזה דרך המזון הראוי.

Nahmanides' Holy Epistle - the Third Path - the Food that is Fit for [Human] Composition

And accordingly that which they [our Sages] said (Niddah 71a) that a person must sanctify himself at the time of [sexual] relations, so too is food included in this sanctity, for it is proper for a person to eat foods that are fit and proper averaging between hot and cold, and they should be from substances that generate pure and clean blood for afterwards that same blood in the future will be transformed into a drop of [seminal] seed and in the future will be the foundation for the creation of a fetus that will be born form such a composition. For if the food is bad, murky, and thick, then the drop will be filthy, thick, and murky. Accordingly, it emerges that the food which is consumed before the composition [of the fetus] is its cause, it is a preparation for it [the fetus] to be wise or foolish, righteous, or wicked. So here into your hands are an instruction that is a great key. Know that since the matter is as we have stated, Hashem may He be blessed juxtaposed in His holy Torah the portion of isha ki tazri'a (“when a woman conceives”) to maakhaloth assuroth (forbidden foods) and said (Leviticus 11) to separate between the pure and impure and between the hayah (non-domesticated animal) which may be consumed and the hayah which ought not be consumed, and juxtaposed it to isha ki tazri'a, and juxtaposed after it the portion of neg'aim (blemishes/plagues). And these three portions [correspond] to a wonderous secret. And the portion of ki tazri'a is in the middle in order to inform you that if a person separates himself from bad foods, he will have children that are proper holy and pure, and if not then behold neg'aim will be anew upon them from the aspect of the drop of seed that was from those forbidden and detestable foods. And by means of this it comes to inform you that a person needs to also sanctify himself with proper foods close to [the time when one conducts] relations so that his seed will be clean and pure and intermediate between north and south, as we have said. And here we have informed you that according to the food [one has consumed] will be the blood that contributes to birth, and according to the blood will be the seed, and according to the seed will be the fetus born from it. And you already know what I have told you, that an eagle will not come from a horse and lentils will not come from wheat, and similarly it ought be said that nothing is born from murky and bad seed except blood that is tainted and abominable, as was stated “the wicked are astray from the womb” (Psalms 58:4). And here I have informed you on this path of the proper path for food.

It ought be noted that while many have traditionally attributed this work to the Ramban, its authorship has been debated amongst scholars. To learn more about the larger work see the entry on Encyclopedia.com and this informative auction listing on Virtual Judaica.

Answer 2

I have searched for this Ramban the whole day since you posted the question. Unfortunately, I haven't found it either. Maybe there is an old manuscript from the Ramban's commentary that Rav Biderman uses here.

In the meantime, I've found an explanation from Rabbi Akiva Eiger. He asks (quoted by Rabbi Moshe Bogomilsky in Vedibarta Bam, parashas Tazria):

Parshat Shemini concludes with the topic of kosher and non-kosher foods. What is the connection between the end of Parshat Shemini and the beginning of Tazria, which discusses child-birth?

And answers:

The Torah is teaching us that the parents’ obligation to a child does not begin when he is born, but exists even when he is in his mother’s womb. The pregnant mother must be careful with the food she eats, because it can have a positive or negative effect on the child, depending on whether it is kosher or not.

Rabbi Akiva Eiger is quoted in saying that:

In Hebrew, a woman who gives birth is known as “chayah.” Thus, the Torah tells us: “lehavdil bein hatamei uvein hatahor” — “to distinguish between the pure (child) and, G‑d forbid, the contaminated (child)” — is contingent on “uvein hachayah hane’echelet” — “the distinction between a ‘chayah,’ — a mother who was lax during pregnancy in the observance of kashrut” — “uvein hachayah asher lo tei’acheil” — “and a mother who was careful not to eat food of questionable kashrut” (11:47).

Gut Shabbos!