Bg 6.42

atha va yoginam eva
kule bhavati dhimatam
etad dhi durlabha-taram
loke janma yad idrsam

Word for word: 
atha va — or; yoginam — of learned transcendentalists; eva — certainly; kule — in the family; bhavati — takes birth; dhi-matam — of those who are endowed with great wisdom; etat — this; hi — certainly; durlabha-taram — very rare; loke — in this world; janma — birth; yat — that which; idrsam — like this.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Or [if unsuccessful after long practice of yoga] he takes his birth in a family of transcendentalists who are surely great in wisdom. Certainly, such a birth is rare in this world.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Birth in a family of yogis or transcendentalists – those with great wisdom – is praised herein because the child born in such a family receives a spiritual impetus from the very beginning of his life. It is especially the case in the acarya or gosvami families. Such families are very learned and devoted by tradition and training, and thus they become spiritual masters. In India there are many such acarya families, but they have now degenerated due to insufficient education and training. By the grace of the Lord, there are still families that foster transcendentalists generation after generation. It is certainly very fortunate to take birth in such families. Fortunately, both our spiritual master, Om Visnupada Sri Srimad Bhaktisiddhanta Sarasvati Gosvami Maharaja, and our humble self had the opportunity to take birth in such families, by the grace of the Lord, and both of us were trained in the devotional service of the Lord from the very beginning of our lives. Later on we met by the order of the transcendental system.