Once of age, they too have a responsibility as residents of this earth to research the truth.
And if they accepted an explanation such as that without questioning the premise of lawful heterosexual intercourse, you either worked hard to give them a (somehow) palatable wrong answer and hence deceived or misled them for whatever reasons - you are responsible, OR you just gave the best answer in your mind despite it's innacuracy, whether innocently or lacking care - again your responsibility.
The level of gravity of the error is known only to Allah, and is more estimable by the person who made the statement and those affected than anyone reading the o.p.
It would be difficult to find a single human being on earth who hasn't made well meaning errors in conveying information since it is the heavily influenced war torn human mind which is receiving, processing, storing, and relaying information.
If it is important that you specifically find a person or persons to convey correct information that would otherwise be difficult for them to obtain, and lack of such information would affect them significantly without your clarification (if it's clarifiable), then it may be a responsibility hovering above your head.
If it's something that they have a responsibility to research for themselves, and it is generally considered as being unreasonable that you should be required to spoonfeed them information despite having not intended any wrongdoing in Allah's sight, it may be best to focus on your own struggles.
Advice to myself primarily - useful to be careful in handing out answers like cheap candy, sometimes some people take for granted undeserved liberties and ask questions demanding answers for which they care nothing - but rather the milkable value and the level of confusion they can cause.
Good outspoken master- Tribute to Ceasar?
Working for the pentagon's army?
Maybe ask them which way the south wind blows and wot happens next by way of complimentary rhetoric if you suspect they're being conniving a-holes.
Please read up on the commentary and background of the following verse:
وَمَا أَرْسَلْنَا مِن قَبْلِكَ مِن رَّسُولٍ وَلَا نَبِيٍّ إِلَّا إِذَا تَمَنَّىٰ أَلْقَى الشَّيْطَانُ فِي أُمْنِيَّتِهِ فَيَنسَخُ اللَّهُ مَا يُلْقِي الشَّيْطَانُ ثُمَّ يُحْكِمُ اللَّهُ آيَاتِهِ وَاللَّهُ عَلِيمٌ حَكِيمٌ
Chapter (22) sūrat Al-Haj (The Pilgrimage) , Verse 52
Sahih International:
And We did not send before you any messenger or prophet except that when he spoke [or recited], Satan threw into it [some misunderstanding]. But Allah abolishes that which Satan throws in; then Allah makes precise His verses. And Allah is Knowing and Wise.
Pickthall:
Never sent We a messenger or a prophet before thee but when He recited (the message) Satan proposed (opposition) in respect of that which he recited thereof. But Allah abolisheth that which Satan proposeth. Then Allah establisheth His revelations. Allah is Knower, Wise;
Yusuf Ali:
Never did We send a messenger or a prophet before thee, but, when he framed a desire, Satan threw some (vanity) into his desire: but Allah will cancel anything (vain) that Satan throws in, and Allah will confirm (and establish) His Signs: for Allah is full of Knowledge and Wisdom:
Shakir:
And We did not send before you any messenger or prophet, but when he desired, the Shaitan made a suggestion respecting his desire; but Allah annuls that which the Shaitan casts, then does Allah establish His communications, and Allah is Knowing, Wise,
Muhammad Sarwar:
Satan would try to tamper with the desires of every Prophet or Messenger whom We sent. Then God would remove Satan's temptations and strengthen His revelations. God is All-knowing and All-wise.
Mohsin Khan:
Never did We send a Messenger or a Prophet before you, but; when he did recite the revelation or narrated or spoke, Shaitan (Satan) threw (some falsehood) in it. But Allah abolishes that which Shaitan (Satan) throws in. Then Allah establishes His Revelations. And Allah is All-Knower, All-Wise:
Arberry:
We sent not ever any Messenger or Prophet before thee, but that Satan cast into his fancy, when he was fancying; but God annuls what Satan casts, then God confirms His signs -- surely God is All-knowing, All-wise --