agi ttaemune suryeongini jibe isseossseupnida.

때문에 means because of, due to, or on account of.

In 아기 때문에 수령인이 집에 있었습니다, the structure is:

• 아기 때문에 = because of the baby
• 수령인이 집에 있었습니다 = the recipient was at home

So 때문에 connects the cause to the result.

A very important pattern to remember is:

• noun + 때문에 = because of noun
• verb/adjective stem + 기 때문에 = because someone does / something is

Examples:

• 비 때문에 늦었어요. = I was late because of the rain.
• 아파서 and 아프기 때문에 can both mean because I am sick, but -기 때문에 is the more direct match to this grammar pattern.

Because 때문에 attaches directly to a noun.

So the pattern is:

• 아기 때문에
• 비 때문에
• 일 때문에

You normally do not put 이/가 before 때문에.

So:

• 아기 때문에 = correct
• 아기가 때문에 = incorrect

Think of 때문에 as a postposition-like expression that already attaches to the noun phrase.

수령인 is a fairly formal word meaning recipient, especially in administrative, delivery, mailing, or legal contexts.

You might see it in situations like:

• package delivery
• registered mail
• official forms
• pickup documents

In everyday conversation, native speakers often use more natural expressions such as:

• 받는 사람 = the person receiving it
• 받는 분 = a more polite version

So the sentence is grammatically fine, but 수령인 sounds formal and a bit bureaucratic.

The 이 is the subject particle.

• 수령인 ends in a consonant sound (ㄴ), so the subject particle is 이
• If a noun ends in a vowel, you use 가

So:

• 수령인 + 이 → 수령인이
• 아기 + 가 → 아기가

Here, 수령인이 marks the recipient as the subject of 집에 있었습니다.

Using 이/가 presents 수령인 as the grammatical subject in a fairly neutral way.

• 수령인이 집에 있었습니다 = the recipient was at home
• 수령인은 집에 있었습니다 would put more topic or contrast on the recipient

So 은/는 might sound more like:

• As for the recipient, they were at home
• or possibly the recipient, at least, was at home

In many cases, both are possible, but they carry slightly different emphasis.

Here, 이/가 is natural if you are simply identifying who was at home.

Because 있다 uses 에 for location.

• 집에 있다 = to be at home
• 학교에 있다 = to be at school

Use 에 with 있다 and 없다 to mark the place where someone or something exists or stays.

By contrast, 에서 is usually used for the place where an action happens:

• 집에서 공부했어요. = I studied at home.
• 회사에서 일합니다. = I work at the company.

So:

• 집에 있었습니다 = correct
• 집에서 있었습니다 = generally unnatural

있었습니다 is:

• past tense
• formal polite style

Breakdown:

• 있다 = to be, to exist, to stay
• 있었습니다 = was / were

This style is common in:

• formal speech
• announcements
• reports
• business settings
• written explanations

Other versions of the same verb:

• 있었어요 = past, polite but less formal
• 있었다 = plain style
• 있었습니다 = formal polite

So this sentence sounds somewhat formal overall, which matches the formal noun 수령인.

No. The sentence does not explicitly say whose baby it is.

아기 때문에 only says that the baby is the reason. It does not tell you:

• whose baby
• whether the baby was the recipient’s child
• whether the baby was in the house
• exactly how the baby caused the situation

That information would have to come from context.

If you wanted to make it clearer, Korean could specify more:

• 수령인의 아기 때문에 = because of the recipient’s baby
• 아기가 있어서 = because there was a baby
• 아기를 돌봐야 해서 = because they had to take care of the baby

Not always, but it often feels neutral-to-negative, or at least like a factual cause.

For example:

• 교통 때문에 늦었어요. = I was late because of traffic.
• 비 때문에 못 갔어요. = I couldn’t go because of rain.

In your sentence, 아기 때문에 can sound neutral, but depending on context it may slightly suggest that the baby was a burden or at least the reason something happened.

If you want a clearly positive meaning like thanks to, Korean usually uses 덕분에:

• 아기 덕분에 웃었어요. = Thanks to the baby, I smiled.

So 때문에 is not automatically negative, but it is not as warmly positive as 덕분에.

It is grammatically correct, but it sounds somewhat formal and a little context-dependent.

Why it may sound slightly unusual in everyday speech:

1. 수령인 is formal.
2. 아기 때문에 is somewhat vague without more context.
3. In conversation, speakers often use a more specific or natural explanation.

Depending on what you want to say, native speakers might also say things like:

• 아기 때문에 집에 있었어요. = I/they were at home because of the baby.
• 아기가 있어서 집에 있었어요. = I/they were at home because there was a baby.
• 아기를 봐야 해서 집에 있었어요. = I/they were at home because they had to watch the baby.

So the original sentence works, especially in a formal or written context, but there are more natural conversational alternatives.

That is very common in Korean.

Korean often puts background information, conditions, or reasons before the main clause. So:

• 아기 때문에 = reason first
• 수령인이 집에 있었습니다 = result after that

This matches a common Korean pattern:

• reason + result
• context + main point

English can do this too:

• Because of the baby, the recipient was at home.
• The recipient was at home because of the baby.

Korean strongly favors putting the reason before the final verb, since the verb usually comes at the end of the sentence.