Bg 1.41

sakaro narakāyaiva
kula-ghnānāṁ kulasya ca
patanti pitaro hy eṣāṁ
lupta-piṇḍodaka-kriyāḥ

Word for word: 

sakara — such unwanted children; narakāya — make for hellish life; eva — certainly; kula-ghnānām — for those who are killers of the family; kulasya — for the family; ca — also; patanti — fall down; pitara — forefathers; hi — certainly; eṣām — of them; lupta — stopped; piṇḍa — of offerings of food; udaka — and water;kriyāḥ — performances.

Translation: 

An increase of unwanted population certainly causes hellish life both for the family and for those who destroy the family tradition. The ancestors of such corrupt families fall down, because the performances for offering them food and water are entirely stopped.

So sakaro narakāyaiva, so those who are Varna Shankar when they grow up they actually are uncultured and they created a life that is hellish narakāyaiva,

kula-ghnānāṁ kulasya ca, so for whom they do this? They do this for the people who destroyed the family and for that particular dynasty also because what happens is they are going to populate the world and when they populate the world they will disrupt everyone not just their family or their opponents family because they are uncultured they are uncontrolled they will disrupt everyone and then what happens Arjuna is seeing much further also, we see that Arjuna is very thoughtful person, and he is thinking in terms of long term consequences here.

patanti pitaro hy eṣāṁ, what will happen because of this is the ancestors will fall patenti pitaro, pitras are the ancestors, patanti pitaro hy eṣāṁ,

lupta-piṇḍodaka-kriyāḥ, lupta for them, piṇḍa, offering of food, Udaka-kriyāḥ, offering of water, kriyāḥ, those rituals.

In Vedic scriptures it is described:

SP Purport: Such help rendered to forefathers is a family tradition, and those who are not in devotional life are required to perform such rituals.

Debts or Rina

So we take things from them so in return we need to give them

But if somebody starts service the Supreme Lord and take Shelter of that Lord Mukunda wholeheartedly then one is not obligated to anyone else he simple serves Krishna and all other debts are taken care of. Since Krishna is giving care through all other living entity so if we serve Krishna alone and directly they we are no longer obligated to them. So here Arjuna is not thinking from devotee point of view he is thinking from Kshetriya point of view.

Simply by performing devotional service, one can deliver hundreds and thousands of forefathers from all kinds of misery. It is stated in the Bhāgavatam (11.5.41):

devari-bhūtāpta-nṛṇāṁ pitṝṇāṁ
na ki
karo nāyam ṛṇī ca rājan
sarv
ātmanā ya śaraa śaraya
gato mukunda
 parihtya kartam

“Anyone who has taken shelter of the lotus feet of Mukunda, the giver of liberation, giving up all kinds of obligation, and has taken to the path in all seriousness, owes neither duties or obligations to the demigods, sages, general living entities, family members, humankind or forefathers.” Such obligations are automatically fullled by performance of devotional service to the Supreme Personality of Godhead.