Learn Hardcore Japanese: musuko mo musume mo soto de supootu wo suruno ga suki da kara, kotosi no huyu ha amari byouki ni naranai to ii desu. - Since both my son and daughter like playing sports outside, I hope they don’t get sick much this winter.

AもBも slightly highlights each one individually: “my son and also my daughter.”
AとBは treats them more as a group: “as for my son and daughter (as a set)…”

In normal conversation, both are acceptable. も…も is especially common when stressing “both / neither / all” (and with negatives: AもBも～ない = “neither A nor B …”).

What does the particle で after 外 mean in 外でスポーツをする?

で marks the place where an action happens.

外でスポーツをする
“Do sports outside” / “Play sports outdoors.”

Compare:

外に人がいる。 – “There is a person outside.” (に marks location of existence.)
外で食べる。 – “Eat outside.” (で marks location of the action.)

So here, 外で says where the action スポーツをする takes place.

Why is it スポーツをするのが好き and not just スポーツが好き?

Both are possible, but they focus slightly differently.

スポーツが好き
- Literally “(I) like sports.”
- Focus on sports as a thing in general.
スポーツをするのが好き
- Literally “(I) like doing sports.”
- Emphasizes the activity of playing sports.

In this sentence, 外でスポーツをするのが好き highlights that they like the act of playing sports outside, not just liking sports as an interest or as spectators. In English you’d usually translate it as “like playing sports” or “like doing sports.”

What is the の in するのが好き doing? Why not just スポーツをするが好き?

Here の is a nominalizer: it turns a verb phrase into a noun-like thing.

スポーツをする – “to play sports”
スポーツをするの – “playing sports” (as a noun phrase)
スポーツをするのが好き – “(I) like playing sports.”

You cannot say スポーツをするが好き; 好き describes a noun-like thing, and the の (or こと, see below) is needed to do that.

You could also say:

外でスポーツをすることが好き – also correct, very similar meaning.

の is a bit more casual and is extremely common in speech; こと feels a bit more formal/neutral or written.

Why is が used with 好き (するのが好き) instead of を?

In Japanese, 好き is technically not a verb but a na-adjective that describes the thing you like as the subject of the sentence.

Structure:

X が好きだ – “X is liked” / “X is pleasing (to me).”

So:

スポーツが好きです。 – “I like sports.”
スポーツをするのが好きです。 – “I like playing sports.”

The person who likes (subject in English) is usually marked with は or is just omitted:

私はスポーツが好きです。 – “As for me, sports are liked (by me).”

Using を with 好き is generally incorrect; the standard pattern is Xが好き.

What does から do in 好きだから here? Is the word order fixed?

から is a conjunction meaning “because / since.”

Structure here:

Reason clause: 息子も娘も外でスポーツをするのが好きだ
- から = “because”
Result/hope clause: 今年の冬はあまり病気にならないといいです。

Literally:
“Because my son and my daughter both like playing sports outside, it would be good if they don’t get sick much this winter.”

Word order is:

[REASON] から、[RESULT].

You can swap the order in Japanese:

今年の冬はあまり病気にならないといいです。息子も娘も外でスポーツをするのが好きだから。

This sounds like: “I hope they don’t get sick this winter. Because they both like playing sports outside.”
Putting から in the middle of the sentence (as in the original) is more typical in written style and clear explanations.

Why is it 今年の冬は with は, not 今年の冬に or something else?

Here 今年の冬は uses は to mark this winter as the topic:

今年の冬は – “As for this winter, …”

It sets up this winter as the time frame we’re talking about, then comments on it:

今年の冬は／あまり病気にならないといいです。
“As for this winter, I hope (they) don’t get sick much.”

Alternative nuances:

今年の冬にあまり病気にならないといいです。
Grammatically possible but less natural; に would simply mark the time “in this winter,” without the topic nuance.

Topic は here implies a contrast or focus: (At least) this winter, I hope they won’t get sick much.

What does あまり mean in あまり病気にならない? I thought it means “very.”

あまり (or あんまり) almost always goes with a negative and means:

“(not) very / (not) much / (not) often.”

So:

あまり病気にならない
“Don’t get sick very much / very often.”

Key pattern:

あまり + positive verb → usually wrong or very unusual.
あまり + negative verb → “not very / not much / not often.”

Examples:

あまり勉強しない。 – “I don’t study very much.”
あまり寒くない。 – “It’s not very cold.”

In your sentence, あまり病気にならないといいです is naturally translated as “I hope they don’t get sick much (or at all) this winter.”

Why is it 病気になる with に? How does ～になる work here?

～になる means “to become ~.”
The particle に marks the resulting state.

病気 – “illness,” “sickness”
病気になる – “to become sick,” “to get sick / fall ill”

So:

有名になる – “become famous”
先生になる – “become a teacher”
大人になる – “become an adult”
病気になる – “become sick”

In this sentence:

あまり病気にならない – “not become sick very much / not get sick (often).”

What does ～ないといいです mean in 病気にならないといいです? Is it “it will be good if…” or “I hope…”?

The pattern [plain form] + といいです is a common way to express hope / wish politely.

病気にならないといいです。
Literally: “If (they) don’t get sick, that will be good.”
Natural meaning: “I hope (they) don’t get sick.”

More examples:

明日、雨が降らないといいですね。
“I hope it doesn’t rain tomorrow.”
試験に合格するといいですね。
“I hope you pass the exam.”

Nuance:

With です/ですね, it’s polite and somewhat neutral.
Without です or with なあ, it sounds more personal/emotional:
- 病気にならないといいなあ。 – “I really hope they don’t get sick.”

Who is the subject of 病気にならないといいです? It’s not written anywhere.

In Japanese, the subject is often omitted when it’s clear from context.

Earlier you have:

息子も娘も外でスポーツをするのが好きだから…

So the topic in the speaker’s mind is 息子 and 娘 (the son and daughter). When they say:

今年の冬はあまり病気にならないといいです。

the unspoken subject is:

（息子も娘も）今年の冬はあまり病気にならないといいです。
“I hope my son and daughter don’t get sick much this winter.”

Japanese relies heavily on context like this; once a topic is established, it doesn’t need to be repeated.

Can I use こと instead of の in スポーツをするのが好き? Is there any difference?

Yes, you can:

外でスポーツをするのが好きだ。
外でスポーツをすることが好きだ。

Both are grammatically correct and mean essentially the same:
“(They) like playing sports outside.”

General tendencies:

の: more casual, spoken, often feels a bit more immediate or concrete.
こと: a bit more formal or abstract, common in writing and set expressions.

In everyday conversation, の is usually more natural in this kind of sentence.

Could I say といいなあ instead of といいです? What’s the difference?

Yes, you can say:

今年の冬はあまり病気にならないといいなあ。

Differences:

といいです / といいですね。
– Polite, neutral.
– Suitable in most situations, including talking to people you’re not very close to.
といいなあ / といいな
– Casual, personal, emotional.
– Often said to yourself or to close friends/family.
– Adds a feeling like “I really wish / I really hope…”

So the original といいです is polite and safe; といいなあ sounds more like an intimate wish.