70. Where does the soul come from?
(Comp 70) The spiritual soul does not come from one’s parents but is created immediately by God and is immortal. It does not perish at the moment when it is separated from the body in death and it will be once again reunited with the body at the moment of the final resurrection.
(CCC 382) "Man, though made of body and soul, is a unity" (GS 14 § 1). The doctrine of the fait affirms that the spiritual and immortal soul I created immediately by God.
To deepen and explain
(CCC 366) The Church teaches that every spiritual soul is created immediately by God - it is not "produced" by the parents - and also that it is immortal: it does not perish when it separates from the body at death, and it will be reunited with the body at the final Resurrection (Cf. Pius XII, Humani generis: DS 3896; Paul VI, CPG § 8; Lateran Council V (1513): DS 1440). (CCC 367) Sometimes the soul is distinguished from the spirit: St. Paul for instance prays that God may sanctify his people "wholly", with "spirit and soul and body" kept sound and blameless at the Lord's coming (1 Th 5:23). The Church teaches that this distinction does not introduce a duality into the soul (Cf. Council of Constantinople IV (870): DS 657). "Spirit" signifies that from creation man is ordered to a supernatural end and that his soul can gratuitously be raised beyond all it deserves to communion with God (Cf. Vatican Council I, Dei Filius: DS 3005; GS 22 § 5; Humani generis: DS 3891).
(CCC 368) The spiritual tradition of the Church also emphasizes the heart, in the biblical sense of the depths of one's being, where the person decides for or against God (Cf. Jer 31:33; Dt 6:5; 29:3; Isa 29:13; Ezek 36:26; Mt 6:21; Lk 8:15; Rom 5:5).
(Next question: What relationship has God established between man and woman?)