Mi hija se parece a su madre.

Because parecerse a is the standard Spanish structure for to look like / to resemble someone.

• parecer on its own usually means to seem
  • Parece cansada = She seems tired
• parecerse a means to resemble
  • Se parece a su madre = She looks like her mother

So in this sentence, se parece a is the correct verb pattern.

It looks reflexive, but here it is best understood as part of the verb parecerse a.

In other words, learners should usually memorize it as one unit:

• parecerse a alguien = to resemble someone

So although se is a reflexive-looking pronoun, the sentence does not mean that the daughter is literally doing something to herself. It is just how this verb is built.

Because the verb is parecerse a. The a is required by the verb.

So the pattern is:

• X se parece a Y

Examples:

• Me parezco a mi padre = I look like my father
• Te pareces a tu hermana = You look like your sister
• Mi hija se parece a su madre = My daughter looks like her mother

This a is not optional.

Yes — su can be ambiguous.

Depending on context, su madre can mean:

• his mother
• her mother
• your mother (formal usted)
• their mother

In this sentence, the context usually makes it clear that su madre means her mother, referring to mi hija. So the idea is My daughter looks like her mother.

If Spanish speakers want to make it clearer, they can sometimes add more information, for example:

• Mi hija se parece a la madre de Ana
• Mi hija se parece a su propia madre

But in normal conversation, context usually solves the ambiguity.

Because the subject is Mi hija, which is third-person singular.

Conjugation of parecerse in the present:

• yo me parezco
• tú te pareces
• él / ella / usted se parece
• nosotros/as nos parecemos
• vosotros/as os parecéis
• ellos / ellas / ustedes se parecen

Since mi hija = she, the correct form is se parece.

No. That sounds wrong in standard Spanish.

To express resemblance, you need parecerse a:

• Correct: Mi hija se parece a su madre
• Incorrect: Mi hija parece a su madre

Remember:

• parecer = to seem
• parecerse a = to resemble / to look like

Usually, parecerse a is very commonly used for physical resemblance, but it can also refer to similarity in general, including mannerisms or personality, depending on context.

For example:

• Se parece a su madre físicamente = physically
• Se parece mucho a su madre en el carácter = in personality

So the sentence often suggests appearance first, but it does not have to be limited to that.

Yes. That is also correct.

Two common ways to express resemblance are:

• Mi hija se parece a su madre
• Mi hija es parecida a su madre

The version with parecerse a is often the more natural, everyday way to say someone looks like someone else.

You can also strengthen it:

• Mi hija se parece mucho a su madre
• Mi hija es muy parecida a su madre

Because Spanish normally uses possessive adjectives with close family relationships when you want to show whose family member you mean.

So:

• mi hija = my daughter
• su madre = her/his/their mother

Using la hija or la madre would usually sound less natural here unless the people have already been clearly identified in context and you are speaking more specifically about them.

You would make the subject plural, and the verb would also become plural:

• Mis hijas se parecen a su madre

Changes:

• mi → mis
• hija → hijas
• se parece → se parecen

Notice that su stays the same. Spanish possessive su does not change for gender, and it only changes to sus if the possessed noun is plural.