The first locus for catechesis, the domestic Church:
255. Parents are the primary educators in the faith. Together with them, especially in certain cultures, all members of the family play an active part in the education of the younger members. It is thus necessary to determine more concretely the sense in which the Christian family community is a locus of catechesis. The family is defined as a “domestic Church”, (Cf Lumen Gentium 11; cf Apostolicam Actuositatem 11; Familaris Consortio 49) that is, in every Christian family the different aspects and functions of the life of the entire Church may be reflected: mission; catechesis; witness; prayer etc. Indeed in the same way as the Church, the family “is a place in which the Gospel is transmitted and from which it extends”. (Evangelii Nuntiandi 71) The family as a locus of catechesis has an unique privilege: transmitting the Gospel by rooting it in the context of profound human values. (Cf. Gaudium et Spes 52; Familaris Consortio 37a) On this human base, Christian initiation is more profound: the awakening of the sense of God; the first steps in prayer; education of the moral conscience; formation in the Christian sense of human love, understood as a reflection of the love of God the Father, the Creator. It is, indeed, a Christian education more witnessed to than taught, more occasional than systematic, more on-going and daily than structured into periods. In this family catechesis, the role of grandparents is of growing importance. Their wisdom and sense of the religious is often times decisive in creating a true Christian climate.
I think I would quibble with the characterization of catechesis in the family as “occasional.” “On-going and daily” is better, at least as the most effective ideal. Nowhere else is the faith transmitted through action and personal example than by parents. Do we exemplify “profound human values”? If so, then our efforts will be fruitful.
We talk quite a bit about parents being the primary educators in the faith, but how much of baptism preparation is devoted to that instead of an esoteric theology adapted from a grade school presentation. If we had to communicate one thing during baptism prep, I’d say it would be to give the tools of evangelization of one’s own children.
What do you think about grandparents? Are they still a decisive factor, or has the moment passed?
Catholic Sensibility 
Maybe it’s “occasional” in the sense of adapted for a particular occasion, rather than education about a planned topic (systematic). Ex: If at Mass you detected that your child needs help on prayer, then you talk about that instead any other topic you had in mind. This interpretation also makes “more occasional than systematic” not redundant with the next statement, which seems to be focused on the times.
Good point, Pablo. Thanks