About Tanto...como and the English translation of your example.

Question

In your example on the use of tanto...como, one of your sentence  has left me uncertain about the translation. Tanto cuando son pequeños como majores, los hijos siempre preocupan a los padres. The English translation in your example is: Whether they are young or grown-up, children are always a worry for their parents. The use of the personal "a" before the word "los padres" suggests that the children worry about the parents, except that the verb should have been "se preocupan"..If it was intended to mean that the parents always worry about the children whether young or grown-up, in my opinion, the words "los hijos" and "los padres" should be interchanged, with the verb se preocupan. Otherwise  " están ocupados" should have been used instead of "preocupan"  and or used before los padres. Please advise.

Accepted Answer

Hola Reynold
In this sentence we've used the most natural translation in English. This means that the translation may not be literal. 
The verb preocupar(se) in Spanish can be used in two different ways:
1. algo (or alguien) preocupaa alguien (non pronominal, with an indirect object using "a")
Here we say that something/someone worries someone. This is the structure we used in:

Ese niño preocupa mucho a sus padres.
That boy worries her parents a lot.

This, however, sounds a bit odd in English; it'd sound a bit more natural to say "that boy is a worry for her parents" or "Those parents are often worried about their boy"
That "a" used in the Spanish "a sus padres" is indicating an indirect object pronoun. The subject in this sentence is "ese niño".
2. preocuparse por/de alguien (pronominal)
We can also use this verb pronominally, for example we could say:

Los padres se preocupan mucho por su hijo.
The parents worry a lot about their son.

Here, the subject is "los padres" and the verb is used with a reflexive pronoun.
Both structures would be correct in Spanish.
I hope this clarified it. 
Saludos
Inma